Michio was born to peasants who moved to the growing industrial city. The transition was hard for them. Instead of working on family farms, Michio's father worked at a shipyard for a wealthy mechant family and his mother worked as a secretary in the same company. Wages were low and the job took much of their time. So, Michio was left to largely fend for himself from the age of five.

As he grew up, he so too did his strength. As a boy, he could beat teenagers; as a teen, he could beat the meanest of the Yakuza gangsters or dockworkers. Thus, he found work as a guard at Shumon House at a young age. After the war, his job was more a bouncer than guard with Shumon being converted from an entertainment place to a brothel and drug pit.

Michio quickly rose through the ranks mostly through force of his physical strength and his will to attain greater status and pay. At the same time, to achieve what he needed, he carried out his missions of intimidation under the guise of the supervillain, Number One. On his twenty-fourth birthday, Michio killed the owner and his family, put them into a box, and hurled it deep into the Pacific Ocean. As Chief of Security he claimed ownership of Shumon House and threatened violence against the three others of equal rank, the Madame, the Gambling Boss, and the Drug Procurer.

Over the past few decades Michio has, by force of will and intimidation, made Shumon House prosper like no other underworld establishment. With the proceeds, he built Shumon Houses around the world and recruited others to help him ensure the growth of Shumon House under a legitimate umbrella corporation, Ichiban.

Michio believes that the ultimate goal of living is to enjoy oneself. While he doesn't really care all that much who he steps on to gain his enjoyment, he has a sense of honor. If someone has helped him out, he'll return the favor at some point. As with many a boss of underground organizations, the public watches what he says and does because they believe that his legitimate businesses are just a cover. Perhaps because of this, he has not been known to back down from anything that he has said.

"You know that Ichiban means Number One, The Best. You are facing the best and nothing but the best."

Number One is a superstrong uber, perhaps one of the strongest in the world. He is also tough, but not to the degree that one might expect. Still, he prefers to work through intimidation and likes to save his strength for situations when someone 'calls his bluff'. Then, he likes to really show that he can back up words with violence.

Michio favors wearing a white tuxedo at most times. And when he's not, he wears a formal silk kimono. As Number One, he wears a costume of red with black boots, belt, gloves, and mask.