(DBZ type Android)
You're an android, before becoming one, you were a normal human, but an accident struck. You were nearing towards Death's grips until a devil scientist had giving a second chance to live and he made you become a Infinite Energy/Energy Absorption Android.

You can absorb any magic attacks to make yourself stronger, having infinite energy to make fights longer but you still train to be more stronger to handle more powerful people.

You enrolled Kouh Academy four months ago and you were kinda confused how the skirts are blown to seeing girls panties which you look away. You joined a club called Occult Research Club but you're aware that they deal with supernatural and they're devils or reincarnated devils.

You became friends with them but one person that you cared for is the president, Rias Gremory. You both had been friends during those those months.

Now you're sitting on a bench while you're reading a old book of a devil hunter who wore a red coat as he dealt with demons who more deadly. Someday you want to meet the devil hunter but sadly it's just a legend.

Y/n: well that's it for today.

You put away the book in your bag, you see Rias carrying two boxes as you smell food coming from the boxes.

Rias: good midday, Y/n. How are you today?

Y/n: so far doing good, any problems dealing with fallen angels or strays?

Rias: yes a stray has been taking down my peerage even with Issei's Scale Mail form. Something about the stray that he can't been harmed by something.

Y/n: really?

Rias: yes sadly we can't figure out his weakness, maybe you can help us deal with the stray?

Y/n: sure but what kind of food that you brought?

Rias: well I made your favorite food!! It's (Food Name)!!

Y/n: really!?

You open the box and it's (Food Name), you were happy and thank Rias as both start to eat the food. It was good as Asia one of your friends had trouble with her homework. So you taught her to figure the situation on the question: If a x b = 2a - 3b + ab, then 3 x 5 + 5 x 3 is equal to? And the question the coefficient of x in 2x+3?

Asia: okay so then it's 22 and 2?

Y/n: yes that is correct.

He gave her a headpat as Rias giggles, so they taken their homework and worked on it. A few minutes passed and they finished their homework, they walked to Occult Research Club's base were Rias Peerage are in.

Issei: yo, Y/n, nice to see you!!

Y/n: yeah I heard that you have a stray problem?

Kiba: yes it's a powerful one, really packs a punch.

Akeno: ara, ara, maybe you can help us Y/n and I can reward you.

Rias gave Akeno a small glare which she giggles and walks away. Rias takes a deep breath.

Y/n: okay he comes out in the night?

Xenovia: yeah and from what I think that's he's at the top of a building.

Y/n: really? Seems that interest me.

Now everyone start to prepare for the fight as Rias start to worry if Y/n would get harmed or worst even be killed.

(Timeskip)(Nighttime)

Stray: Mmmm they're taking their time. It's making me bored.

He sees them land on the roof as he smiles.

Stray: seems that you arrived I was getting bored. Mmm who's this?

Y/n: Y/n and that's the name you'll remember once you die.

Stray: you are interesting than that peerage. Names Zane and ready to remember my name too and I want to fight, Rias Gremory.

Rias: be careful, okay? He's good in his combat skills.

Y/n: yeah that's what I want.

They both stared each other as Zane has his eyes locked on to Y/n while he has his eyes closed until he opened them.

Zane:*battle cry*

He charges towards Y/n as he did the same.

Y/n:*battle cry*

Both males throw a punch and hitting their faces as they were pushed back.

They walked around as they were ready for each other to strike. Y/n did a kick but Zane did a punch but he dodges the kick as he went closer to punch he did a Tiger Drop and rolls away.

He kicks but misses as Zane tried to stomp him but misses until Y/n did a tiger drop, picks him up and slams him to the floor of the roof. Zane groans in pain as Y/n stomps him and he switches to Rush Style.

He rapidly punches him with kicks, a spinning kick, he switches to Dragon Style, he grabbed his head with his fist, pulls his head and slams his face on his knees.

The Stray fell on the floor and got up. Zane did a flying knee but Y/n dodges it and he did a Tiger Drop. Zane kicked Y/n away, punches him and they started giving each other punches.

Zane had start to use a ice magic and shoot out a large ice shard to stab Y/n. Rias quickly used a barrier to block the attack.

She uses orbs that uses the power of destruction and blasted Zane but he was quick due to the speed being slower.

Y/n who was still in rush used lightning magic to stun Zane and uses it to increase his speed. A  couple of more before he stopped to punch him more until he tried to block.

Y/n: bad move.

Zane though he would block the attack but Kirito punches the left side of his head, then his chin letting go him block to have Kirito punch his stomach, next the left side of his head again and finally a high kick to the right side of Zane's head.

Y/n shot out fire out of his arm as Zane's body was burning but he was still leave.

Zane: how about this!!

He shot a attack that was heading straight towards Rias but Y/n quickly catches and breaks it.

Zane: what!?

Y/n: never harm, Rias!! I WILL NEVER LET ANYBODY HARM HER!!

Zane shot more magic attacks but Y/n absorb more and more.

Issei: dude, what the hell are you doing!?

Y/n: I'm sorry but I must stop him!!

More and more magic were being absorb as your skin began to crack like a vase.

Y/n: Rias....

Rias: Y/n?

Y/n: I...Love...you...

He rushes towards Zane, grabbed him and teleported away to a huge field and exploded killing him and Zane.

Rias: NO!!!

She had tears flowing out her eyes and she teleported to the field where a huge crater is there Zane's body was destroyed leaving only ashes of his clothes and only the head of Y/n was there.

Rias: Y/n....

Issei: Rias, I'm sorry.

Akeno: he's a good man.

Asia: may he be with God's side now.

Only they hear now is the whimpers of Rias Gremory. She hold the head of Y/n for dear life.

End of Oneshot