Born into a pretty normal and typical family with neither parents turning out to be heroes. A father, who had a engine quirk allowing him to build up and manipulate the energy in his body to be built up and stored for later use, which came in handy against fatigue or simply when tired and a mother with a weak force quirk allowed her to apply weak pushes on what she touched. These two quirks would come to define Samada's own individual quirk as the doctor would tell him upon hitting puberty.

Samada would grow up with a father who worked as lumberjack that was known as man with unlimited energy while the exhaust vents mutation growing from his shoulders helped to prevent burnouts. Whereas the father relied on his quirk, his mother, on the other hand chose not to pursue hers and instead ran a small cooking show and often let Samada be her little helper with cooking.

Growing up, he was a relatively normal and behaving kid that like most, also came to enjoy superheroes and would join other kids to read comics. It was the set of vents on his back; a mutation coming from his father being the one thing that really stood out about him, though they had no use or purpose at the time and so mostly kept them hidden beneath a shirt.

Since the age of five, Samada always loved superheroes; one in particular who inspired him especially. A sport themed hero had gotten his attention at the age of seven and ever since wanted to be like him and gotten into the habit of trying out a myriad of sports, though most tended to end with him in bruises and scrapes. He wasn't one for getting angry easily, but the constant failing to find a sport that fit him left him frustrated and this went on for nearly a year until Samada had enough. It would all change upon nearing the age of eight, when one day stumbling upon a softball and his frustration reaching its peak and this fit of rage would lead him to learn of his talent at pitching after seeing the ball vanish in the distant.

That day was a turning point for the boy who had been stuck in a rut the past year and ever since he would practice his pitching. Spending long hours of the day checking to see how far and fast he could throw, while through testings came to learn he was ambidextrous, leaving him capable of pitching with both hands. Yet, he still favored the right hand and his father, who saw this and used some of his breaks to toss the ball with him.

These alone time with his father, who was otherwise busy most of the time were some of his favorite memories and at this time received valuable advice. Being told that, though his pitching was stronger with the right hand and instead to only use his left hand around others and this confused him at first. When asking why, his father told him that if he planned to be a hero or go into sports that keeping a hidden trump card could come save him from a dangerous situation one day. And so, Samada came to solely use his left hand when in public while making sure to keep practicing with his right in secret, giving him something only he and his father knew.

Not long after, he joined the kid's league baseball team, taking the position of pitcher as expected. He always played his best to make his parents proud, while keeping the hopes of being able to use the skills gained from this in the future as a possible hero. Yet, those dreams weakened as he watched kids around his age gaining quirks as he showed no sign of one still, only having the useless vents on his back.

Two years passed since then and nothing much had changed and now at the age of ten with no hint of a quirk popping up as noting changed. That is, until his cousin, Tetsuo suddenly appeared at their footsteps along with some officials one day to hear something terrible had happened. What exactly happened, he never found out and seeing the state his cousin was in, thought it best not to ask; simply learning Tetsuo would be living with them from then on.

He did not mind at all and found it could actually be fun to have Tetsuo living with them along with being good to be with family after the incident. Even if Samada didn't know his cousin all that well since the two didn't get to really hang out much, but it didn't matter and made him a promise to be there and support him long as needed, instantly treating him as part of the family.

Living with Tetsuo had been strained and awkward at first, though not once did Samada give up on trying to cheer him up, coming to see him as a younger brother, though his being somewhat cold and distant made things somewhat difficult.

After two years of living with them; Samada's overly optimistic ways started getting to Tetsuo or at least he hoped as he made sure to have his cousin join him in any game or activity. He refused to hang out or associate with someone that tried to exclude or treat him badly as he became protective of him.

Just when things between the two were improving and everything with the family going well, then puberty would hit the now twelve year old. A normal process that all boys and girls went through, but for Samada it would turn out to be a very life changing experience. After years of dreading he might not get a quirk and that very night that puberty struck; jump starting his quirk which would throw his body out of whack.

On that night; nothing would be the same as his body would constantly create energy causing a disruption in his metabolism and the first spew of smoke from the vents which had been inactive for all his life and awakened him.

Life became very exhausting and hectic for the next six months with him needing to figure out an eating schedule due to his metabolism being sped up. This left him needing to eat two and sometimes three times the quantity of food humans normally ate, though it didn't bother Samada too much, though with it meant being unable to partake of anything with caffeine or high sugar content. He hated having to give up most candies and with a mom, who worked as a chef giving him books and pamphlets on healthy food.

Along with the multiple repeated doctor visits to figure out just what was going on with his body and whether if it was started by a quirk, what exactly it was. It took several blood and tests to find that his quirk had made his body into a living generator while it took an accident to learn of what exactly its purpose was.

An incident involving him flicking peas with a spoon out of boredom as a sudden spew from the vents caused him to jump in surprise. The sudden shock having him send the spoon flying straight through the glass window of the hospital door of his bedroom and embed into the wall across from his bedroom. From there, it was revealed he was able to transfer energy his body created through his hands to give objects instant momentum without needing to build up or actually apply force.

From that moment on, he would be put through special training regiments to work out how his quirk worked and to try and properly control it, but all that energy made it very difficult for Samada to fully concentrate and gather his mind, which greatly impacted any progress. None of it discouraged him, however, instead sparking his hopes of being a hero and this dream turned into his motivation.

The next three years would be painful and exhausting with all the training sessions and forced diet restriction. Samada endured it all of it; thanks to his parents for being the pillars that kept him on his feet and his friends, especially Tetsuo giving him support, keeping him from giving up.

And finally the determination to fight for what he aimed for; to become a hero and though that goal was still a ways off, the first step being the acceptance into Kosei Academy.

When asked why he wished to joined the academy he would give two reasons:

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To inspire the youth whether weak or strong to never back down for through the worst of it, you'll have family and friends to act as your strength.

That is the kind of hero Samada Isinui aims to be.

A quirk that has caused Samada's body to continually create an abundance of energy that he is able to channel and concentrate into both his hands and fingers. That energy then can be transferred into items or objects that he touches which can then be fired off like projectiles instantaneously up to 100 mph. At this current time he can freely fire objects between 0-100 mph without needing to concentrate or exert that much effort.

When he focuses and concentrates while pooling some of the energy, he can boost the momentum to throw upwards to 150 mph, though with some slight strain in his hand muscles afterwards.

Currently his strongest use of momentum is the overburst shot that allows him to greatly propel an object up to 500 mph. Unlike the previous use of this momentum, overburst requires a build up charge taking thirty seconds that comes with a backlash that causes overheating in the arm using it and limits the use of the arm for a certain period of time and so he is only capable of firing one overburst with each each arm. Due to this drawback, this skill is best meant for emergency use.

With him being ambidextrous; allowing him to use both hands for his quirk, though favoring his right hand leaves his left hand slightly weaker. Whereas his right hand being able to throw at the max speed, his left is only able to fire at 135 mph and with overburst up to 450 mph, which he has come to find being a good way to get others to let their guard down.

The mutation of vents gained by his father helps regulate and compensate the energy usage by expelling smoke which can release enough volume to cover one person. Using this greatly lessens the backlash that would otherwise cause intense overheating and burn damage on his arms, though at this current time, Samada is unable to properly control when venting causing him to release at random times which can happen multiple times throughout a day to protect and cool his body.