Disclaimer: First Chapter
Story Start!

A shiver of fear.

"Okay, since the 3 of you are back at full health thanks to Sakura and Asia... time to start the next step in this lesson... Issei!" Naruto pointed to the male of the group. Issei yelped and jumped back, with one of his hands covering his crotch, and the other one covering his face. Naruto deadpanned for a moment at the fearful reaction. "... Calm down, I'm not going to hurt you... just step forward and activate your powered up state." Naruto waved a hand at him.

Issei was confused.

"My... Powered Up state?" Issei didn't remember anything.

Naruto pinched the bridge of his nose.

"Transform... when we were training, and you were on the brink of death, you found a power deep inside of yourself... remember that power... and do it again." Naruto gave a lazy explanation, since he didn't really have the words to say to really go step by step. Naruto looked at Rias and Koneko. "... how about you... Koneko, do you want to use that kitty thing?" Naruto offered.

She was shocked.

"Eh!?" Koneko reached up and placed her hands on the top of her head, only to not feel any cat ears on her head at all. Did her transformation come undone when Naruto was kicking her ass, or did her powered up state that she achieved in the training end up causing her to use her true nature?

Naruto sighed at her reluctance.

He gestured to Rias.

"... How about you, do you want to do the thing where you go blonde?" Naruto offered her.

Rias grabbed her hair, and she looked at it to see that it was still very much red hair. She looked at Naruto like he was insane.

"I did that... the only thing I remember is... a small fire... darkness..."

"Don't tell me... do it... find the power hidden in you, and do it." Naruto stopped Rias from describing it with words. He wanted her to use her actions, and have her body to remember what it went through that caused her transformation. "You two, step aside." Naruto gestured for the other two to back away from her.

They did.

By a large margin.

"... I don't even know what I did."

"Stop talking, and just remember... and do it again. Close your eyes and do it." Naruto crossed his arms.

So Rias closed her eyes.

'... Okay... Remember... remember...' Rias couldn't see anything. She blocked out all of her senses as she focused on everything that she could remember. She took a couple of deep breaths to calm her heart when she remembered the great fear that she felt when she almost died... when she was kept at the edge of death and not allowed to pass on. She stopped even sensing the magical power around her.

When she opened her eyes, she wasn't in the real world.

Rias looked out at an endless void of darkness, and in front of her was a red flame that emitted a dark and terrible power... but a warm power for her. She looked around, and all she could see around her was the void. Nothing at all anywhere, but her own body and the flame in front of her. She didn't know what to do.

Inside of the flame, where was a smaller flame.

Rias hesitated, before she reached out and stuck her hand inside of the flame... and she grabbed the smaller flame that was inside of the red flame.

Rias opened her eyes for real.

She was back in the real world, and she felt an amazing power engulf her body and soul. Red magical might came out of every pour of her body, her red hair transforming into a golden blond as the red flames of her magic power formed a great aura around her. The flame settled inside of her chest as warm fire filled her blood, and she felt wild.

She felt wild and powerful, hard to control, and great magic brimming underneath the surface of her skin.

"Woah." Koneko whispered in awe as she sensed a huge difference in magical power from Rias. Before, she had been around a higher level of High Rank Devil in terms of raw power and magic. Now, with just her transformation alone, her magical power in size and potency was close to the same level as Grayfia. It was a huge boost to raw power that seemed absolutely insane to anyone that had meet Rias, and also sensed how much power Grayfia had.

Koneko gulped.

"Woah!" Issei shouted and jumped back in amazement.

"This is your ultimate potential. Your power at it's peak. From here on, the only way for you to grow any stronger is to learn to master this power." Naruto had taken her to the edge of life and death, and then brought out this power for her. Rias was radiating a power that would normally be way to much for her to control. She was leaking much to much power at the moment for the transformation to hold up and be stable.

"My peak?" Rias asked in shock.

She felt unstoppable, like she could defeat anyone.

"All your latent strength at least... if you can master this power. This form will consume a lot of stamina, since you're using power your body isn't ready for. So... take a few deep breaths and calm down." Naruto raised his hands up and gestured for Rias to bring down the amount of power she was using. Her current form was powerful, but the stamina drain was going to weaken her if she kept wasting so much power like she was.

Rias followed his instructions and calmed herself down.

The power decreased, and the red aura on her skin weakened until it was barely visible. Her hair stayed blonde, and the power was still there... just still hidden deep inside of her.

"How... how do I stop?" Rias asked, and the act of speaking caused her power to fluctuate again.

Naruto took some deep breaths, and she copied him, getting her power back under control once more. The smallest of actions caused her to nearly lose control of all the great power in her body.

"How did you turn it on?" Naruto asked her.

"... When I closed my eyes... I was in a dark space with a fire... and inside that fire was another fire... so I reached in and grabbed it."

"Okay, take your hand out of the fire." Naruto had the answer now. Rias closed her eyes and imagined herself taking her hand out of the fire, and the power faded from her body. Her red hair returned, and she collapsed backwards with a large amount of sweat starting to form on her body.

The second the power left her, she was exhausted.

"What..."

"That form consumes a lot of your stamina. It's like..." Naruto thought about it for a moment. "... driving one of those car things! Right now, you are always putting her foot on the gas. You don't have the ability to just... go at the speed limit. You're body is going at full speed... that form gets bad gas mileage!" Naruto explained it with a snap of his fingers.

"How do I-"

"Issei's turn now." Naruto raised a hand to stop Rias.

Issei, with more confidence after seeing Rias succeed, stepped forward with an actual excited look. He summoned his Sacred Gear, the red gauntlet on his left arm, and held it out. He closed his eyes.

"... I want to grab boobs! The biggest of knockers... when you almost killed me, to comfort myself, to stay sane... I imagined all the breasts in the world I wouldn't be able to grope if I died..." Issei explained word for word the experience that he felt when he unleashed his own hidden power. The green gem on top of his gauntlet started to shine brighter. "... and I refused to fail!"

There was an explosion of power.

The red gauntlet extended and became a dragonic armor that covered his entire body, with 2 large dragon wings coming out of the back of his armor.

"Welsh Dragon Balance Breaker!" Issei's armor called out for him.

"Ooooh." Rias clapped her hands together awkwardly. It would have been a lot more badass in her opinion if Issei had kept his mouth shut, instead of explaining what he did to mentally achieve that power.

"Another Stamina Drainer of a form... 2 in a row... and activation condition aside, this one gives a big boost to defense with the armor... okay then... 1... 2... 3... 4... 5... 6... 7... 8... 9... 10... 11... 12... 13... 14... 15." Naruto started to count, before the armor on Issei's body shattered, and he collapsed to his knees in exhaustion for a moment. Naruto had been able to sense a huge drain on Issei's stamina. "... okay, so Issei..."

"Yeah?"

"Your power is awesome... but it isn't your power is it?" Naruto asked.

Issei showed his Sacred Gear, and looked down at it.

"... It is my power... but it isn't my power."

"Gotcha, well, it seems that you can only use it for 15 seconds right now. That form drains a bunch of your stamina, so the only way for you to improve that power right now is to increase your stamina." Naruto clapped his hands together and explained. It was a great power, but because Issei lacked stamina to properly use it, he would just need to train that for now.

Everyone looked at the nervous Koneko.

"I... don't feel comfortable using my power... if it is what I think it is." Koneko didn't go into any further detail.

Naruto sighed.

"Okay, so hard way it is. If you won't use your power-" Naruto grabbed Koneko by the forehead.

*Pop*

Koneko's cat ears and cat tails popped out of her body, as a flood of Senjutsu power entered her body against her will. She jumped back from Naruto, startled by her forced transformation, only to look down at herself.

She didn't go insane.

She felt a huge amount of power get transferred to her.

"Well... I transferred a bit of Senjutsu chakra to you to force you to transform back into that form I saw you use. Good thing I'm a master of Senjutsu, or I wouldn't have known what you used." Naruto rubbed his chin as he saw the changes in her body much more clearly than before. Koneko was too busy feeling out the changes deep within herself to notice. "I don't understand why you're reluctant, you're super cute like this." Naruto was just confused.

Of the 3 of them, Koneko had the least of a boost to her power unlocked from the training. It was still an explosive boost to her magical abilities, but compared to Rias and Issei, her power had experienced the least of a boost.

Unlike their forms though, Koneko's didn't drain her stamina nearly as much, she could also replinish this form by just absorbing more energy from her surroundings. It was a good power if you used it wisely. Unlike with Rias, since this was a power that she gained by absorbing power around her and combining it with her own, she could drastically improve it by improving her own base power.

Rias' Power Up: Unlocking her Max Potential, the Peak of her Power.
Issei's Power Up: Pushing his Sacred Gear to it's current limit.
Koneko's Power Up: Senjutsu

"Super cute." Rias agreed.

"Senjutsu is a fine power, and as you grow stronger, your Senjutsu will... Issei?" Naruto looked at a confused Issei.

"What is Senjutsu?"

"Simple, Senjutsu is like ice cream. You add the power of nature around you, and swirl it with your own power to create a more powerful new power. Still-" Naruto flicked Koneko and knocked all of the Senjutsu chakra out of her. Since he forced the power into her, he could easily just force it out of her the same way. "-among the three of you, her power is the one that she will have to train to make stronger."

"You just-"

"You have to train your stamina... and Rias, to conserve your stamina, you have to train to control your magic..." Naruto started to explain.

Koneko wasn't listening.

'My life flashed in front of my eyes hundreds of times when I was close to death... was I wrong about Senjutsu... was I wrong about my sister... the sister in my memories... seems different than the sister who...' Koneko had so many questions.

Senjutsu didn't feel dangerous to use like she thought it would be.

It felt natural.

"Okay Issei, I want you to work on your stamina in your base form... No Boosted Gear... by..." Naruto pushed a boulder to the edge of the mountain they were on, and caused it to roll down the mountain. "... Pushing that boulder back up the mountain. We still have 2 days left to train... which will leave you 1 day of rest before your Rating Game." Naruto explained.

Rias stepped forward.

"My training?" Rias asked.

"Just meditate while entering your powered up form, and try to conserve as much power as possible. Try not to let your magic power leak out of you like a broken faucet." Naruto didn't have much training that he could offer her in such a short amount of time. Naruto looked at Koneko, about to offer her some training as well.

She raised her hand to stop him, so he nodded his head and waited for her to speak.

"...Naruto-sensei..." Koneko got down on her hands and knees, ass in the air as she placed her forehead against the grass. "Please... spar with me using Senjutsu." Issei and Rias both looked at Koneko in horror.

She wanted to spar again.

"Why?" Naruto asked her.

"... I have to understand this power... please don't ask me why. I don't want to talk about it."

"Okay then, no questions asked. So... since a spar is going to be too one sided to be fair..." Naruto reached into his bag and pulled out scroll. "Take this scroll from me using Senjutsu, that will be your training." Naruto wasn't the type to hold back on somebody... in the way that you would think.

Naruto didn't underestimate his opponent, but at the same time, he didn't believe that each and every attack should be lethal. He would usually just use enough force needed to neutralize the enemy, or to cancel out their attacks if possible. Even if he used Senjutsu against Koneko, he would have to pull his punches to a level where he didn't just murder her.

Senjutsu was just THAT powerful.

"No, don't hold back."

"Koneko, once I stopped a house sized rhino easily and threw it... up into the clouds. If I were to throw somebody your size... I could send you to the actual moon if I tried." Naruto wasn't so much as underestimating Koneko, as he was accurately gauging how strong she was and how strong she would need to be to be anywhere near a threat to him.

He would use Sage Mode against her, but the fact was that his normal form was all that it would take to easily beat her.

Koneko stood up, and bowed.

"Okay you idiots, get to training. We only have 2 days, because you slackers took the entire 3 days to unlock your hidden power." Naruto clapped his hands together.

...

"Sir... I noticed this earlier when I was getting changed... but... why do I have a scar on my penis?" Issei didn't remember anything happening to him downstairs.

"It got ripped off during training. Don't worry, you were so out of it, that you didn't even feel it. I convinced Sakura to add a little bit of..." Naruto muttered to Issei in his ear. He didn't know if he got everything, so he convinced Sakura to add 2 inches just to be safe. That way, unless Issei lost 3 inches or more, he should get a small increase to his total size down there once he had the ability to get a boner again.

Apparently, medical ninjutsu could be used to take a person's hair, and transform it into flesh to graft onto a missing body part. Shizune had apparently used that method to heal a hole in Neji once before, and Sakura used that technique to graft newly created flesh onto Issei.

Issei had a bald spot on the back of his head, where Sakura had to shave off enough hair to turn into flesh.

"... So... how long until..." Issei whispered back.

"... 6 weeks until you can get a boner again. Again, as a man, sorry about what happened. You got a boner during training while you were afraid of death, and when I punched you, your penis got caught in a boulder and ripped off... I didn't touch it with my bare hand. Nothing gay happened." Naruto assured Issei for his mental health.

"Thank you."

"For what?"

"I was about average before, if you added anything, I might be a little above average now... You might have just improved things for me." Issei was excited to one day being able to make use of his extra length.

"I'm pretty sure you lost an inch, so Sakura adding 2 inches only gave you 1 extra inch. It isn't going to be super noticable. You don't need to thank me, I just felt bad about what happened. Also..." Naruto looked at Rias and Koneko, who were both confused as to why Naruto was whispering to Issei. "... trust me when I say, those 2 don't remember it... but you getting your penis ripped off was... perhaps the least painful thing to happen to the three of you."

"I... don't want to know what happened to them." Issei looked at the two ladies and paled.

"I'm going to be honest... I didn't know a woman's body was even capable of doing something like that... they are really lucky they don't remember the... accidents that happened to them. Also... I turned Koneko into a pretzel... she got a taste of her own ass."

"It's a nice ass though."

"... aaaaand that conversation is over. Back to training!" Naruto was done when Issei said that, so he clapped loudly.

Back to training.

Chapter End!
Please Leave Me Lots of Nice Long Reviews, But No Flames Please!

Blonde "Super Rias" is an actual DxD transformation Rias can learn that brings her very close to Satan-levels of power, not something that I invented as a transformation.