"This is the worst…"
Sento Kiryu, Kamen Rider Build, found himself in a bad situation. He had picked up reports of a horde of Smash fairly far out of the city, and went off to investigate the cause. Turns out, they were simply remnants of a previous attack, causing havoc like berserk wild animals. Normally, he would've taken them out by now with ease, but in his arrogant thought process, he thought that the Smash would be a smaller group, not a massive horde like this.
The fact that he had left a good chunk of his other bottles back home only made things worse. And that part didn't even matter much either, since the Smash barely let up on attacking, not giving him a chance to even switch, much less transform in the first place. Shake, dodge, repeat. There was never an opening for him to insert the bottles into his Build Driver. He couldn't even get a chance to call Banjou for help.
"Damn, they're persistent!"
Sento managed to avoid one of their mighty punches, and kicked off, jumping skyward. Only to find himself jumping towards a small cluster of Noise.
"Oh crap…"
He braced himself, but widened his eyes as he saw the cluster of Noise go up in a small explosion. He landed safely, looking around for the cause.
"Are you okay?!"
Sento looked over to a hill, where he saw a figure in blue armor with some kind of arm cannon. Judging from the tone of voice, it was a girl.
"Yeah! Thanks for the save!" Sento called back.
"You should get out of here!" She shouted. "It's not safe!"
"Don't worry!" Sento said, holding up his bottles. "You gave me the opening that I needed!"
He shook the two bottles, before aligning their caps and sticking them into his driver.
[RABBIT! TANK! BEST MATCH!]
The girl looked in confusion, as Sento started cranking the lever on his device. She widened her eyes when complicated mechanisms started to shoot out of it, creating some sort of armor mold. There were two halves, one red, one blue.
"Wha-?"
"Henshin!"
The two sides drew towards one another, before clasping on Sento and encasing him in the suit. There was a hiss of nebula gas from the cracks, as the finishing touches sealed up.
[HAGANE NO MOONSAULT! RABBITTANK! YEAH!]
Sento struck a dramatic pose, much to the seeming surprise from the Smash. He had donned a unique armor of red and blue. One eye was shaped like a rabbit, and the other was shaped like a tank.
"What is that…?"
"Coming through!"
Sento jumped up into the air, before coming down with a huge stomp, sending a shockwave that sent the Smash flying.
"He's strong…"
"Behind you!"
The girl turned around to a Smash trying to pounce on her, only for Sento to kick off the ground towards it, and deliver a powerful haymaker that obliterated it in one shot.
"Now we're even." Sento said, turning to her. "Can I get your name?"
"Uh, I'm Aile." She said.
"Okay, Aile." Sento said. "I'm really fascinated by your armor, but I think we should hold that talk off for now, yeah?"
The two of them looked at the oncoming Smash.
"Good call." Aile said, before turning her arm cannon at the horde, charging it up. She fired a massive blast that took out a good chunk of them.
"I think a little switch up will help us out." Sento said, pulling out two more bottles, one yellow, one purple.
"Huh?" Aile said, as she continued blasting. She watched as Sento shook the bottles and swapped them with the pair that were already in.
[NINJYA! COMIC! BEST MATCH!]
He cranked the lever again, and the same test tube machines came out, this time with a yellow half and purple half.
"Build up!"
The two halves converged on Sento again, changing his appearance.
[SHINOBI NO ENTERTAINER! NINNINCOMIC! YEAH!]
Sento was now in a yellow and purple form with a scarf. His eyes were shaped like a pen and shuriken. He summoned a comical looking sword out of the air, before pressing a trigger on it, lighting up one of the panels.
[BUNSHIN NO JUTSU!]
To Aile's surprise, several copies of Sento materialized out of the air before they started attacking the Smash with quick and deadly sword swipes.
"The best backup is oneself." Sento said.
Aile was just confused, but also in awe. The clones started to dissipate, leaving only one Smash left.
"There we go." Sento said. "Wanna finish this one up together?"
Aile shook off her confusion and nodded. "Right. Can you get that thing to stay still?"
"I got just the thing for that." He said, smirking under his helmet.
Sento pulled out his red and blue bottles again, before sticking them back into his belt.
[RABBIT! TANK! BEST MATCH!]
"Build up!"
[HAGANE NO MOONSAULT! RABBITTANK! YEAH!]
He turned back into his previous form, confusing Aile again.
"Just give me a second!" Sento said, holding up his hands before he ran towards the Smash. "Do the charge up thing with your weapon!"
"But-"
"Trust me!" Sento called back. "The law of victory has been set!"
Aile followed his advice and aimed her arm cannon, hoping that Sento would jump out of the way.
And jump Sento did, right over the Smash… before breaking through the surface of the ground and disappearing.
"What the-?"
The moment Sento fell through the ground, a white energy chart ensnared the Smash, locking it in place. Sento rose out of the ground on a pillar of stone, and dove down the chart line with his foot outstretched.
[READY?! GO!]
"Now!" Sento shouted to Aile.
"Right!"
Aile fired off her blast at the Smash, while Sento dove towards it.
[VORTEX FINISH! YEAH!]
Sento's kick and Aile's energy blast hit the Noise at the same time, sending it up in a plume of flames.
"And that's the end of that chapter." Sento said, pulling out his bottles and cancelling his transformation.
Aile walked over to him, turning back to normal. Sento saw that she was fairly young, with short brown hair.
"Um, who are you?" She asked him.
"Me?" Sento asked, before holding up a hand next to his head. "I'm the genius physicist, Sento Kiryu. Also known as Kamen Rider Build."
"Kamen Rider?" Aile said. "Well, I'm Aile. I guess you can also call me Mega Man."
"...but you're a girl." Sento said.
"Ha ha, yeah. I get that a lot." She said, scratching the back of her head.
"So how did you transform?" Sento asked, walking around her. "How you fought was incredible."
"Oh um, I use these things called biometals." She said.
"Biometals?" Sento repeated. "That's amazing. You're a real hero, huh?"
"I'm not sure about that." Aile said, rubbing her arm. "Upholding the legend of Mega Man is a big responsibility. I'm not sure if I live up to that."
"Nonsense." Sento said. "You saved me earlier."
"Huh?"
"Let me tell you something. You can't see it under my helmet, but when I help someone, I can't help but grin from ear to ear." Sento said.
"So what you're saying is…?"
"Saving someone is just as important to being a hero." Sento said.
"...thank you, I needed that talk." Aile thanked him.
"Happy to help."
Sento received a notification from his phone, seeing that it was from Misora.
"Man, I got to go." Sento said. "The life of a hero never ends, you know?"
"That I can understand." Aile said. "I need to leave as well."
"If we ever cross paths again, let's work together." Sento suggested.
"I can get by that."
Wishing the other good luck on their journeys, two of them shared a quick hi-five, before going their separate ways.
The legend of Mega Man ZX and Kamen Rider Build would continue on.