Author's Note: Hey everyone, its been quite a while since I last uploaded and I am sorry for taking so long, but as I had said before, I had wanted to get this chapter just right and not rush straight through it after the fiasco I had with that bad review. So please forgive me for being late on the upload, but I truly hope that this chapter, the Pairing Chapter that I had promised, is here. And the winners from the results were... MIKUTSUYU! And so in order to celebrate this pairing, I officially dub it Ranavirus! For those who don't know Ranaviruses are viruses that attack Reptiles and Amphibians (And before you bring up Tsuyu's middle school friend being a snake woman, the idea for Mikumo and Tsuyu being in the relationship is still up for consideration). Oh and I'm also trying to work out a Side Project that I will work between Viral Toxin Chapters, and it will be a fanfic where Mikumo replaces Izuku and the original version of All Might, Valiant, will be taking All Might's place. What i want from you guys is to go to my profile, in which I will put up a poll that will end on Christmas Eve, to decide what I should do for Mikumo's Quirk, as I have 3 great ideas for it. Anyway thats enough of my rambling, here is Chapter 4 Ranavirus Part 1! WEB SWING!

Chapter 4: Ranavirus Part 1

As everyone gathers on the training field for their first Hero Course Class, Mikumo is trying to calm himself down and analyze everyone's costumes, only for somebody to tap his shoulder. "Mikumo-chan!"

"Huh?" Mikumo jumps a bit and turns to Tsuyu, "Oh Tsuyu, it's you! Please don't scare me like that!" Mikumo says, breathing a sigh of relief. "Anyway, what's up?"

"Well I was wondering what was going on with you and Uraraka, you seem rather nervous around her!" Tsuyu explains. "Do you have a crush on her?"

"N-no! Not really…" Mikumo says, "To be honest I don't know why I get so flustered around her, it's almost like something about her seems to set me in those kind of fits."

"Really?" Tsuyu asks, "Well you seem rather normal around me, are you sure it's not anything else?"

"I am sure!" Mikumo says, then notices her costume, "On another topic, I think you look kinda cute in that suit!" He notices the frog theme going with her suit, smiling big as he walks around and looks at her. "High performance flippers with suction pads I believe, same on your gloves…"

"Could you stop that? It's kinda creepy…! Gero..." Tsuyu says.

"S-sorry about that!" Mikumo says, "Geez, I can be as bad as Izuku when it comes to costumes and him with quirks…" The young man is chuckling a bit nervously, but as he scratches the back of his head, Tsuyu decides to check out his costume a bit as well, which appears to be a skin-tight jumpsuit with the image of Biohazard Symbol on his chest, whilst wearing a reinforced leather coat, a cravat round his neck, with a highly decorative belt around his waist that has studs, a buckle shaped like a biohazard symbol, thick reinforced leather boots with heavy straps, and finally, a full face mask that has two large white eye lenses that have an almost glass-like luster to them. Unlike Izuku's which has a hunter green and white coloring to them, Mikumo's crimson red with navy blue highlights, thanks to Virus revealing his true colors, literally. Tsuyu smiles as she looks at him, a single sentence crossing her mind.

'He looks kinda cool, but then again…' She looks to see Mikumo's muscles being present through the suit. 'It leaves nothing to the imagination…!' She blushes a bit and turns her head away, 'Calm down, Froppy, now's not the time to get flustered!'

"Alright everyone! Today for our first Hero Training Class, we'll be performing an Indoor Mock Battle of Heroes vs Villains!" All Might says, "Now the goal of this little exercise is that those assigned the Villain Title will be guarding a Mock Explosive inside their designated "hideout" the Hero Team will wait 5 minutes so the Villain Team can find their payload and get into position before storming the hideout after them. If the villains or the payload are captured, the heroes win, but if the villains can keep them busy for a full 15 minutes or capture the Heroes, the Villains win!" He then brings out a raffle box. "Alright, now everyone stepforward and draw a letter, whoever matches you, you're teamed with them!"

"Are we really using this to decide out teams!?" Tenya asks, shocked

"Just think of it this way, Iida-kun!" Izuku says, "Pros often don't get a choice in who their partners are in many situations, and are sometimes forced to work with those they don't know! We could use this to simulate those situations!"

"Ah, I see, always thinking two steps ahead! My apologies, All Might-sensei!" Tenya says, bowing.

"Alright then, everyone, draw your lots and meet up with your partners!" All Might calls out, in which everyone goes and draws their lots, with Mikumo drawing Team H as his team, and he looks around for his partner, who just so happens to be Tsuyu Asui, the two walk over to each other and as everyone looks for their group, Mikumo smiles as he creates a tendril and sits in meditation.

"I hope we get a decent pair of opponents, honestly, if this turns out to be easier than the Entrance Exams, I'm out of here!" Mikumo says

"You really shouldn't say things like that, Mikumo-chan, you really could get yourself in trouble!"

"I know, I know… I'm honestly excited, but honestly…" He looks to Mina Ashido, "Something about her is putting me on edge…"

"Ashido? Why her?"

"I honestly don't know, something about that suit of hers feels kind of familiar, and not in a good way..." Mikumo says, looking at Mina with an edge in his voice. 'Virus, is that what I think I it is?'

It certainly is, I had sensed her in the city sometime yesterday, her partner died in combat and it seems she's found a temporary host until the Agents come to retrieve her!

'Is she a benevolent or malevolent?'

Benevolent, until her host starts getting frustrated or angry. She is one of the 5 symbiotes my grandfather was forced to spawn when he was here on Earth during a time in his life that he called Perversion of Life. Virus explains Still you should be cautious about this one. Unknowingly or not, she is a perfect match for that girl, as from what I know, her Quirk generates Acid, and that one specializes utilizing and rebounding chemical based attacks.

'Noted… Thanks Virus, you're getting a treat when we go home today!'

"Mikumo-chan?" Tsuyu asks.

"Huh?"

"We got selected to go up against Team C, which is Jirou and Todoroki!" Tsuyu says.

"Heroes or Villains?" Mikumo asks, frantic.

"We're the Villains…!"

"Fuck…" Both Mikumo and Virus say at the same time.

"Gero?"

"Oh nothing! I guess we should go then!" Mikumo says, Tsuyu showing them the way to their "hideout" and as they enter the building, they take time to find the Bomb. "So Tsuyu, can you tell me about your Quirk?"

"Of course, I can jump fairly long distances, I have a tongue that can stretch about 20 meters, I can stick to almost any surface, I can eat things and eject them from my stomach later, I have a camouflage ability that I'm still having trouble figuring out, and I can secrete a toxic mucus, though all it does is hurt a lot." Tsuyu explains. "Why do you ask?"

"My Quirk is… Symbiosis… My body is the breeding and evolutionary stage of Phage Viruses. However, over the past five years, they have evolved beyond that of viruses, and have become something of a Symbiotic being with an sentience and intelligence of its own." Mikumo explains, "However, thanks to it, I can generate an amorphous suit that is hard, tough and strong, but it has two serious weaknesses…" He looks at his suit, "It's able to be destabilized by powerful sound waves and extreme heat…"

"So what happens if your suit gets hit with these kind of attacks?"

"Pure and undiluted agony…" Mikumo explains "For not only me, but my Phages as well, as they are linked to me on cellular level…"

"So this is pretty much the worst case scenario for you huh?" Tsuyu asks. "So we're going to need to play smart against Jirou and Todoroki…"

"Exactly, and I'm not liking my chances… Fortunately, my viruses are linked to my cells symbiotically, so even if they destroy my suit, i can generate a new one once I've recovered my strength." Tsuyu looks at him and then looks down, thinking.

"I might have an idea, it's a bit crazy but it just might work!"

"What is it?"

As the two discuss their plan, Todoroki and Jirou make their way to the building, both of them walking in silence. As they enter, Todoroki looks around and signal's Jirou to follow him, the young woman looking at him as she stabs one of her earphone jacks into the wall and listens. "Found them, and I think I've found the bomb, too!"

"Where are they?" Todoroki asks.

"They seem to be moving quickly on the second floor, and one of them is…" She then rushes to Shoto and pushes him away. "Right above us!" The roof explodes as spiked tendrils burst through the ceiling and try to pin them down.

"How unmanly!" Kirishima says, glaring at the scream, "Using a sneak attack like that!"

"Miku-kun has to…" Izuku says, stepping forward.

"What do you mean, Midoriya-kun?" Tenya asks.

"The battle suits Mikumo and I wear are linked to nervous system, and we've always had a shared weakness to loud noises and extreme heat. He is probably using his tendrils at their maximum length to attack from a distance." Izuku says. "Knowing him, he already knows a bit about Todoroki and Jirou's Quirks, and for him to attack from a distance is against his Modus Operandi."

"Meaning?" Kaminari asks.

"He's saying that Mikumo is breaking his own code of conduct, knowing he is likely in an overwhelming disadvantage when he considers what their quirks can do." Tokoyami explains. "He's trying to end this fight quickly before they can build up an effective counter attack."

"Then what about Asui?" Ochako asks, seeing Tsuyu reaching into a bag Mikumo had given her and placing red and blue globs of goo in places around the building. "It looks like she's placing something down. Could Akatani be acting as a distraction?"

"Possibly! But it's a very risky move since he's the most powerful player on their team…" Yaoyorozu says. "However, it was possible that Asui's plan could be to set up a situation where they can likely win with Mikumo rampaging to keep the two busy!" Everyone watches the screen as Jirou connects her Jack into one of her boots, Mikumo making a hasty retreat, only for his leg to get caught in it. Although there is no audio on the screen, Izuku, and from the very back Mina, grab their heads in agony, the psychic connection the Symbiote's have spreading the pain across them. "Midoriya!"

"I'm fine, but as I said, our suits are linked with our biology, and have the same manufacturer, so they are meant to work as a team. I can feel whatever pain Mikumo is feeling, but on a lesser scale." Izuku collapses and holds his right leg, to which Mikumo lies on the ground on the floor above, holding his leg as the suit reforms.

"Jirou is going to regret that!" Mikumo says, his mask making a terrifying grin as his anger begins to boil, revealing razor sharp teeth.

Yes… Show her the true meaning of pain… Let's give her a nice taste of… Virus begins, feeling their darker impulses enter their mind, A Viral Infection! The two let out a blood curdling roar, to which Jirou holds her ears while Shoto gets ready to fight, however, Tsuyu places the last glob down and keeps a straight face.

'Alright, the plan is going good so far, now I just need to get back there and back him up!' Tsuyu says, putting a glob over her mouth as it becomes a gas mask with razor sharp teeth on it. 'This is just too weird, though I am grateful that this will keep me safe once these little bubbles pop…' She rushes off as the blobs then start to swell, and makes her way to where Mikumo is, quickly discovering him in the midst of a recover from the Sonic attack. "Mikumo, are you alright?"

"Just fine, your plan worked, I managed to confirm that Jirou does used a Sonic-based fighting style, but she's a range-fighter, which means you'll need to take care of her. I'll focus on Todoroki." Mikumo says, his tendrils telling him the group has left the area. "It seems he is hesitating to use his Flame Generation, which is perfect for me, as my Symbiote isn't affected by the cold he generates."

"So we'll need to seperate them in order to deal with them effectively…"

"Fortunately my little bubbles will burst soon, so now we need to slow them down so they can burst."

"Right! I hope this plan of yours works!"

"What are you talking about? This was your idea!"

"Oh yeah!" Tsuyu says, the two of them rushing off. Tsuyu can't help but notice the mask had changed a bit, the lenses have become more menacing whilst that terrifying maw on it wasn't there before. "Say, Mikumo-chan, is that mask of yours part of your quirk too?"

"How observant you are young miss! Yes, I am part of his Quirk. My name is Virus, it is a pleasure to meet you!" Virus says.

"It's nice to meet you too!" Tsuyu says, to which Mikumo stops and then sends his tendrils down, then pulls up rapidly, having grabbed his quarry.

"I gotcha!" Mikumo says, to which Todoroki starts channeling ice across the tendrils. "Brrrr that's chilly!" He opens the mask via the mouth. "However, only using half of your power is not going to hurt me, pathetic excuse for a hero!" Mikumo slams Todoroki into a wall, shattering the ice on his body all the while sending Shoto into another room. "I don't know why you hold back your flames, but you shouldn't be ashamed of your power, it's yours and yours alone!" Shoto looks at him in shock, "Don't let anyone tell you how to use it, it's yours to command and control as you see fit!"

Shoto looks at the red and blue "villain" in front of him, and his eyes have widened a bit as he looks at Mikumo, who prepares four tendrils to lash out at him. Shoto feels something inside him begin to snap, as a proud and encouraging voice, along with a gentle and soothing one speaks to him. "While it is true that Quirks are usually inherited, but what is important is not the connection to your family, but to your own flesh and blood, and it's your quirk to command and control!" All Might says in his mind.

"You see, Shoto? You aren't a slave of your bloodline, you can become the man you want to be!" Another voice, from that of a woman with pure white hair says, smiling at him, comforting him, whilst Shoto feels heat rising from his scar, and he looks at Mikumo, who stands in front of him, strong and defiant. Shoto places a hand on his scar and sees it bleeding and finds a little injury there, but a smile crosses his face as his blood catches on fire, as does his left side, cauterizing the wound.

"You really are crazy, you know that, Akatani?" Shoto says, "Going out of the way to help your enemy! Aren't you supposed to be a villain?"

"No I'm an Antihero, I break the law to uphold the Law!" Mikumo says, causing All Might to flinch at this declaration, remembering that line from the first time he and Valiant had teamed up. Tsuyu just watches as she sees Mikumo take a stance, then seeing Jirou run up from a nearby flight of stairs, and looks at Mikumo, sending her jacks into her boots.

"Gero!" Tsuyu calls out, sending her tongue at Jirou and knocking her backwards, causing her sonic waves to it the ceiling.

"Ow!" Jirou says, then looks at Tsuyu, who is on the ceiling, looking at Jirou.

"Not going to let you get to him that easily!" Tsuyu says, then checks her watch. '30 seconds left, we have to make these last seconds count!'

"Nice one, Tsuyu!" Mikumo says, rushing to engage Shoto, the screen fading to white. A few moments later, Mikumo is on the ground next to Tsuyu, burns covering his arms and face as he looks to, Tsuyu, who took the full force of Jirou's sonic attacks. It was an utter defeat, but Mikumo can only smile as he begins to lose consciousness.

"The best one in this match was Asui Tsuyu!" All Might says, pointing to the group.

"Gero!?" Tsuyu asks, having regained conscious no more than a minute ago and is caught off guard by the statement.

"Huh? But didn't Todoroki and Jirou win?" Kirishima asks.

"That is certainly true but this is not just a test of teamwork, it is also a base evaluation of your skills to determine a better baseline for future assessments!" All Might explains, "Now can anyone tell me why in had chosen Young Asui as the best of these four?" Yaoyorozu raises her hand, "Yes, Young Yaoyorozu?"

"To be as brief as possible, the reason why Asui is the best of this particular group is due to the fact she came up with a plan that seemed to revolve around keeping their opponents busy whilst she planted those, for the lack of a better term, plastic explosives." Yaoyorozu explains.

"While it was Jirou-san who drew first blood, she had failed to catch up to the Villain Team in time to end the fight quickly." She looks to Jirou, "If she had been smarter, she would've noticed that her Quirk caused Akatani severe pain and would've ended the battle in one fell swoop if she had struck him a second time."

"On the Contrary, Todoroki did little to aid in the battle, and only put in actual effort after Akatani what could be equated to a lecture on heroism and helping him to refocus himself. However, once he had put forth actual effort, it proved to be too much, and now Akatani is currently going to see Recovery Girl to heal from what may cause permanent scarring and nerve damage to Akatani's hands and face."

"As for Akatani, he had followed through with the plan but did the one thing he was not supposed to do and properly goad his enemy into putting in his all whilst there was an explosive in the building, as too much heat could've caused it or those other explosives to erupt and take them all to the grave. There is also the fact that he caused severe damage to the structure, which is something no hero, or even a villain protecting an explosive payload should do, as it could lead to the same explosive end."

"However, Asui had taken the time to speak with Akatani beforehand and had devised a delay tactics strategy with Akatani being the linchpin whilst she placed the explosives." Yaoyorozu explains.

"If I may interject…" Tsuyu says, "Those weren't plastic explosives…"

"Huh?" Yaoyorozu asks.

"They were actually bio-weapons Mikumo constructed from his own body."

"What!?" The students ask.

"It's true, Mikumo's Quirk allows him to generate an armor composed entirely of a virus that is weak against sound and fire, but he can also rip pieces off of his suit to create biological explosives that would've released a cloud of viruses throughout the building that were created to affect anyone within five feet of the building. All it would've done was make Todoroki and Jirou suffer from Dizziness, Drowsiness, and eventually cause them to fall asleep. Mikumo-chan gave me a gas mask made from the material of his suit so I wouldn't be affected once the bombs went off." Tsuyu explains. "The virus would've become ineffective after a few minutes, so it would've been crucial that we delayed them long enough to put them to sleep then tie them up."

"So then why did…?"

"I don't know…" Tsuyu says, looking down. "However, it seems helping Todoroki was more important to him than winning."

"W-Well in any case that is enough for you four, and that was an excellent explanation young Yaoyorozu." All Might explains, "Now Young Asui, please go to check up on Young Akatani and confirm his condition!"

"Yes, sir…" Tsuyu says, leaving after All Might writes her a pass and she goes to where Mikumo is currently located, seeing the young man is lying on a bed, as another person, wearing an orange colored suit is standing near him. "Gero!?" He looks to be dressed in a full body jumpsuit of orange and black, whilst Virus has been separated from Mikumo and is now sitting in a glass beaker with only his head resting out of the top. "Who are you!?"

"Our apologies, young miss, we didn't expect anyone to be visiting these two so quickly…" The suit absorbs into the man's skin, revealing that he is dressed in an odd military uniform with a strange symbol upon it, like that of a white spider gripping onto a black planet. "I am truly sorry for overstepping my boundaries!" He is a man with crimson skin, horns, and a lizard-like face. "I am Rax Tiranoos, I am from the Agents of the Cosmos!"

"I don't think I've heard of your Hero Agency…" Tsuyu says.

"That's because our "Agency" isn't on this planet, I'm from another world…"

"Gero!? You mean like an alien!?" Tsuyu asks, shocked.

"Yes… Anyway, I was passing by in my shuttle when I received a distress signal from Agent Agony, but all I found of her was her suit in a young woman's home, and I tracked Agony here. I am afraid Agony has bonded with one of your fellow students and is merely waiting a return trip home…" Rax explains.

"I see… And is Virus-chan an alien too?"

"Yes, he is from the Planet Klyntar, and is of the race of the same name." Rax explains. "Though I and my partner are proud he has found a partner who is perfectly balanced."

"What do you mean?"

"It's complicated to explain, but suffice it to say that if this boy were an imperfect host, it would've driven Virus insane." Rax explains. "And the only way I am able to speak to you right now is because my partner, Phage, is translating for us."

"I understand, so do you want me to help you retrieve your lost ally?" Tsuyu asks.

"I am sure Agony senses us already, however, she is currently pregnant, so it would be dangerous for her to leave her host in this state. For if she were to spawn, then her child would be corrupted…" Rax explains. "However, I am sure you know the host by this image…" Shows her an image of Mina Ashido.

"I do, she's my classmate, I can bring her here if you want…" Tsuyu says.

"If you could, I could take Agony's spawn and place it in a purification chamber until it's ready to bond." Rax explains.

"Alright, I'll be right back!" Tsuyu says, looking to Mikumo, 'Hang in there Mikumo-chan…' Tsuyu quickly makes her way back to the group, praying that Ashido hasn't been called into the next fight.

"And the next two to enter the battles are Team A as Heroes, and Team D, with Team A as the Heroes and Team D as the Villains." All Might calls out.

"Yes!" Mina says.

'Oh no! I'm too late!'

This is bad… Agony speaks with a strained voice.

'Whats wrong, Agony?'

I'm going to give birth soon, this is just the worst luck I've had in a while!

'Shit!'

"Ashido-chan!" Tsuyu says, "The Nurse needs to speak with you! Something about some blood tests from the hospital!"

'Oh thank god!' Mina thinks, "Oh the results are finally in? Thank goodness! I'll be back in a few!" After they are out of the room, Mina walks with Tsuyu to the Nurse's Tent. "Thanks for that, Tsu… I don't think I could've done this test without those results…" She places a hand on her belly.

"I know about your suit, Ashido-chan…" Tsuyu says, "The Agents have come to retrieve it, but we have a more pressing issue… Agony is Pregnant, isn't she?"

"Y-yeah…" Mina says, shocked but calms down. "If she doesn't find a safe place to spawn, we'll end up with an insane bio-weapon on our hands." Tsuyu leads her back to Rax, who is talking with Recovery Girl about the best treatment options. "Hello!"

"So you're Agony's temporary host, you've come at a most opportune time!" He then brings out what appears to be an egg shell. "Reach into here, and let Agony do what she needs to!"

"Yes sir!" Mina says, a bit perturbed but she knows what needs to be done after Toxin's explanation yesterday. She reaches in and as her hand slips past the crack, a dark purple and turquoise droplet of ooze falls inside, to which Rax quickly seals it with Phage's help and nods as he checks it's condition. "Is that…?"

My spawn…? Yes… I would like to leave her in your care when the training is done today!

"In my care?" Mina asks.

A deal is a deal, isn't it? You helped me get home, while you get a new Symbiote to act as your suit, those were the terms we struck earlier today!

"I know, but…" Agony's face flows out with a head of hair upon her.

I know we haven't known each other more than a day, but I am grateful to you, Mina Ashido, so please accept this honor I give you.

"Alright…" Mina says, looking past the egg's shell and sees a pair of cute little eyes looking back at her. "Oh it's so cuuuute!" She is already in love with the little creature as it begins to grow and fill the shell.

"Well now that that is over, I think you should get back to class…" Mikumo says, sitting up as he regains consciousness. "I won't be able to join for the rest of the day, as my nerves still feel like they are on fire, so I'll keep an eye on the little one until you get back, Ashido-san!"

"Call me Mina, Mikumo-kun, and thanks!" She gently hands the egg to the redhead and nods as he lies back down carefully. "Okay, Agony, let's make this first and last fight together one for the history books!"

This should be fun! Mina smiles at her suit and then rushes off, heading back to the group, to which Mikumo smiles at the two of them.

"I think I will stay here and help you watch over the little one until class is over." Tsuyu says, looking to Mikumo. "There are a ton of things that I want to ask you, but I honestly don't know where to begin!"

"Well, how about I tell you a story and you ask questions along the way?" Mikumo asks.

"That sounds okay to me…" Tsuyu says, looking at him.

Mikumo simply smiles at the girl in front of him and then looks to where Mina had rushed off to, 'The Die has been cast, now it's just a matter of waiting for the results on where the faces land.' Mikumo thinks as he thinks of his cousin and Mina together, and he chuckles to himself. 'Good luck, cousin, knowing how hyperactive that girl can be, you're in for one rough life! One filled with laughter, joy, and an awkward amount of energy.'

Author's Note: Okay its finally done! I've gotten chapter 4 up and finally took the first step in my Ranavirus infection^^ And it feel so good^^ Anyway Thank you guys for your patience and for your support of my fanfiction, it truly means a lot to me. I won't be doing any more Viral Toxin chapters until after I get the first chapter of my Side Project out, and that won't happen until after Christmas, when the poll I've set up for you guys to decide on Mikumo's Quirk for this new MHA Side Project. Also the poll will have a selection of Pairings you can choose from, so choose one Quirk and one Pairing, and the two with the most votes by Christmas Eve will win! Remember, One Quirk, and One Pairing, thats the Rule. Anyway I'll see you guys in the Side Project, whose name I will decide when the Poll ends. WEB SWING!