Tokyo - Three Years Ago:

The story itself all begun at the destroyed entrance of a shopping mall, where a kid attempted to withstand a power mightier than his own. But that's not where the tale itself begins, for it has two quintessential characters. One was a child on a normal routine with her parents, just visiting a famous city for leisure, while the other was a hard-headed delinquent trying to pick fights with whatever seemed to be able to withstand a punch of his power.

The terrifying atmosphere of the wrecked hall was well-nigh palpable, some plant-like mutated creature spread its whip-like tendrils around, impaling and slithering through tons of flesh and bone, tainting the flooring of carmine. Mai's parents advertised her to not open her eyes at any given circumstance, as both covered her with their own bodies. Debris crumbled everywhere, all but a lonesome figure stood to confront the beast. Torso slashed, limbs bruised as he trembled to stay up, a supercilious grin crossing his visage as he jolted forth.

His speed was breathtaking, his raw might making gusts of wind buffet at every jab he hurled towards the half-vegetable, half-humanoid being. Its resistance was remarkable, tanking and shrugging damage off ridiculously easy as its mass of tentacles brushed Toshiro aside, puncturing his body over and over with its keen-edged thorns. The boy spat some blood on the ground, he'd have to get rid of those protrusions one way or another. "Hey, ya freak! Bet ya can't hit me with those silly thin's of yers again!" He yelled, readying to leap as he timed the arrival. The extensions rocketed towards him, swinging viciously in outstanding speed as they lacerated his forehead, rendered inutile his left arms and were rather close to ripping his stomach out of his abdomen.

Hurled against a wall, the impact caused a gargantuan quake, followed by such a timid, yet strident cry. That almost mute cry reverberated inside Toshiro's head as he slowly opened his eyes. The shock was tremendous. He wasn't the only one bracing for impact, how could he be? All that carmine on the ground he had been ignoring until now wasn't his, was it? Obviously not. The area was crowded, people were slaughtered... He wouldn't change his mind so swimmingly if it wasn't for the sight that captured his attention the most. Right aside him, a couple firmly stood, clearly killed by the blow, but with their bodies still bulwarking the fragile kid with tears in her eyes.

That one strident cry inside his head, to represent his guilt.

Among humans like those two, who even in death still guarded what was precious to them, he was the weakest of all. Stumbling his way towards the kid, he collapsed centimeters before her, right besides what seemed like a notebook. The open page revealed a drawing, a somewhat angered young man bearing a pompadour and thick eyebrows. 'Come back soon, big brother.' read the kanji aside it. He raised his head, the kid had disobeyed her own parents, her beady eyes staring fixedly at Toshiro. "Big bro..." She muttered, causing Toshiro's own tears to stream down his eyes.

So that was what crying was like...

The creature continued its attack, violently swinging its tendrils left and right, it all seemed lost. One of those directed toward Toshiro and the little girl. If he took the hit, he'd certainly dismay, it was too strong, even for the Deathless Delinquent. But then the sacrifice of the couple would have been entirely in vain. If he were to succumb there, it'd at least account for something.

Stomping heavily on the ground, he stretched his arms around the kid, the hit quickly slammed against Toshiro's back, his eyes losing the heat they had moments ago... Those were some odd fourteen years, but they had just been crowned. He would have died a veracious hero, if not by one detail, one of the stings stuck on his forearm, being torn apart from the whip-like tentacle and grazing that little kid's face.

Toshiro witnessed as a few droplets of blood came out from her frightened visage, the whole atmosphere burning around him, his fighting spirit rekindled instantaneously as the livid shine on his eyes glistenned stronger. "H-hold on to me, little kid." He stated, raising the kid with one arm. His steps were calm, his sight was crystal-clear, as each of the protrusions boosted his way, he could rapidly distinguish where they would hit, his wounds expeditiously closed, his hands nimbly waved the tendrils off-target. The irrational creature focused all its power on murdering that one persistent human, but its effort proved to be completely in vain. Nothing came even close to hitting him or the amazed kid on his right arm.

As the last desperate attack came his way, Japan's Champ opened his mouth and bit each incoming extension off with clinical precision, halting right before the monster before erasing him with a single punch. More than the claps that soon encompassed the place, from the survivors and authorities and all those bystanders that soon circled the place, more than those kind-hearted words they yelled toward their stoic hero, the delinquent's reward was found on the smile of a child he didn't even know. Embracing her tightly, he could only hearken to her whispers rather than the crowd's vociferous cries. "I knew you would be back, bro."

A few hours later:

Toshiro had been reborn that day, after the defeat of the monster, he aided rescuing the other survivors that were found around the perimeter, even going as far as reuniting families amid the crowd. His strength and speed were quintessential to clear the zone in less time than expected. Much less.

Still, it was time to go home.

Ignoring all the reporters, he grabbed Mai by her arm and walked her to his house, taking his time to get to know her name, age, any closer relatives that would take her... He ended up knowing too much.

The knocking door was quickly open by a rather petite lady, her silvery threads and wrinkled cheeks not lying about her age. She swiftly hugged Toshiro, letting out a relieved sigh. "Toshiro! You're back! And..." He paused for a moment, kneeling to amicably gaze the timid girl behind the adolescent's legs. "Who is the little princess?"

"H-hey, granny! This is..." Toshiro exchanged looks with Mai, nodding a bit as he nervously chuckled. "My little sister, Mai. I finally found her after all these years!" He winked, the old woman responded with a nod, representing her comprehension of the situation. "So this is young Mai, huh?" She shifted her gaze to the kid once again. "Why don't enter and wait for us at the room, sweetie? I need to talk to your brother."

Bowing her head, Mai nimbly darted into the house, portraying all the inherent curiosity of children. The old lady raised from the ground, her much serious stare now focusing on Toshiro, who she raised like a son. "Does she have any family around? She can stay a couple of days until the shock of the accident passes, but I won't be able to feed one more mouth. We won't be kidnapping any children, I hope you know that."

"Look, granny, I know, trust me. But that kid... She thinks I'm her brother, one that died a couple years ago, and now she has just lost her parents because of me... Seems like they didn't have much contact with the rest of the family since their son died and all. And if ya can't feed three mouths, don't worry 'bout me, get her food and I'll... I'll find work one way or another, help out with some salary to pay her stay. I... I can't leave her, her parents died 'cause of me, 'cause I wasn't strong enough, I wasn't fast enough..."

"It's not your fault, Toshiro!" The old lady stopped his discourse, raising her index finger. "You need to stop taking blame for everything, trying to take the whole weight on your shoulders. You saved that kid, what else do you want? She's not your sister! I know you're a good man, I raised you to become one, and you've grown stronger and kinder within the years, but you can't carry all responsibility for this."

"Yer right, granny. I can't carry the weight of the world on my shoulders... I can't hold things too fast, I can't take a few more weak hits like the one that almost knocked me out and killed her parents 'cause I wanted to test somethin'... Yer totally right, I can't do anythin' like that on this selfish, weak form I'm at." He took a deep breath prior to recapitulating. "I can't do anythin' of that yet, but I'll become stronger. Strong enough I'll end these threats like they were nothin', so more brothers don't lose their sisters... So families can see their little daughters smile like she did. If her family wanna get her, they have all the right to do so, but as of right now, she needs me more than anythin', I won't walk there and tell her I'm not family! We ain't family either, and yer the only mother I've known! From now on, little Mai is my sister, even if we don't share any blood relation, at heart she'll always be."

From that day on, Toshiro Shizuka trained hard to remove any barriers he had. He trained hard to become the strongest man alive, to protect not only his sister, but all people he could. To become truly Invincible Under the Sun.