Toshi was born on the Fishman Island, in a wealthy district of town, to the daughter of a wealthy merchant and the martial arts master who trained her brothers. Their relationship was forbidden and secret, so when it culminated in a child, his father was expelled from her family's employ and forbidden from ever seeing Toshi's mother ever again. Shortly before Toshi's birth, his father left the Fishman Island to take up residence on a deserted island in the South Blue to become a hermit. Toshi's mother was heartbroken by his leaving and never recovered emotionally.
When Toshi was a very young child, his mother died of a mysterious illness, leaving him an orphan with his grandfather. This was short lived however, because after his mother's death, Toshi's grandfather sent his fleet of merchant ships to find the island Toshi's father lived on, and upon finding the hermit, Toshi was immediately shipped to the island where he was left with his father, despite his father's aggressive protests.
Toshi and his father's relationship was nearly nonexistent. His father, who he learned was also named Toshi, making him Toshi Junior, made sure he had food and water, but otherwise ignored him, blaming his mere existence for his expulsion from the Fishman Island and the separation of him and Toshi's mother. When Toshi grew old enough to gather food on his own and craft simple necessaties for himself, all contact between the two ceased almost entirely.
As Toshi grew older, he became very resourceful, crafting many useful things from anything and everything he could find around the island. Despite having no education whatsoever, Toshi showed signs of great ingenuity. Toshi's father also seemed to notice this from a distance as well, because one day while Toshi was searching the beached wreck of a massive ship, his father approached him for the first time in years to take him as a student of martial arts.
Toshi's father claimed that his sudden change of heart was due to him believing that he was dieing, and having a desire to pass along his legacy to the next generation. Toshi resented his father for the way he had been treated growing up, but agreed to learn nonetheless. They trained for days on end, never taking breaks. Everything Toshi did became a method of training and growing stronger, and Toshi learned at an amazing pace. Withing a couple of years, Toshi had learned all his father could teach, and had surpassed him in every way.
When Toshi reached adulthood, and had nothing left to learn from his father, he decided that he would leave the island to find a place for himself in the world, as every place he had been so far in life had been unwelcoming to him. His father protested this aggressively, wanting him to stay and remain a hermit of their martial arts style, but Toshi had no interest in spending his entire life on an island alone with his father who had treated him so badly as a child.
The first chance Toshi got, he gathered up his few belongings and swam out to sea, taking up residence on a pirate ship that was passing within sight of the island. They were happy to take him aboard and taught him how to be a skilled cook while he stayed with them.He learned much of the world through the pirates who took him in, and was happy to be traveling with people who were happy to have him around. Toshi spent a few years traveling with these pirates before he decided to strike out on his own to find a different crew who might have need of a fishman cook. It was to this end that Toshi joined the Thousand Sword Pirates, who he has been traveling with ever since.
Toshi is a Ray fishman, who stands just over ten feet tall. His face and chest are a pale grey while his back and the rest of his body is jet black. He doesn't wear any shoes, prefering to leave his webbed feet exposed, and wears shorts made of burlap that are torn at the knees and help at his waist by a length of thick rope meant for hoisting massive cargo. He also doesn't wear a shirt, but instead wears a vest that he made himself form the weather worn cloth of a huge pirate flag that he found in the wreackage of a ship on his home island. The skull and crossbones still adorn his back and depicts a three eyed skull with two long curving horns and a three bone cross underneath.
During his adventures on Kelvin Island, the arctic home of the Shichibukai Bardo, Toshi wrapped himself tightly in fur pelts and took on an appearance of a large patchwork bear.
During the events on Sweet Illusion Island, Toshi dressed up for the candy collecting festivities and wore a large suit of metal armor.