Yuichiro was a short young man with long, straight hair of a dark black color that fades to pale turquoise the closer to his waist it goes. He wore it loose with two clumps protruding slightly from each side of his head, a set of marginally shorter hair left down to frame his face, and unruly bangs over his forehead. He also possessed large, mint-green eyes, a trait, like his hair, that he shared with his twin brother, Muichiro Tokito.
He wore a dark, sleeveless yukata with a white mist design, similar to the lighter one his brother wore when they were both 10.
Yuichiro was a cold and skeptical individual who didn't believe in compassion or caring for others. He believed that doing good deeds wouldn't do a person a shred of good, which is seen when he claimed his father was a fool for dying while trying to gather herbs to help cure his mother's fatal illness, and shot down Muichiro's suggestion that they become Demon Slayers in order to save people's lives. This behaviour likely originated from the pain and grief of losing both of his parents in one fell swoop, however, since just before he passed away from a Demon attack, Yuichiro was seen praying that his brother be saved and apologizing for getting in his way when he wanted to be useful, suggesting that deep down he was actually a kind and caring person.
Yuichiro and his younger twin brother, Muichiro, were born to a woodcutter and his wife. When they were 10, their mother caught a cold which developed into bronchitis and killed her. Their father, away at the time, went to fetch medicinal herbs during a storm and ended up falling off a cliff to his death.
The two siblings survived together, while Muichiro took after the emotive and kind nature of their father, Yuichiro instead held a cold and impassive outlook on life.
In the following spring, Oyakata's wife, Amane, arrived to recruit them for the Demon Slaying Corps. Muichiro's excitement was opposed by Yuichiro's unwelcoming and rejecting reception. In an outburst, Yuichiro revealed that he blamed the death of their parents on their hardworking and selfless nature and adopted a cold outlook, hoping to keep himself and his brother alive.
While Amane continued to visit the twins, Yuichiro chased her away each time. In the following summer, a Demon arrived at their cabin during the night and attacked, and as a result Yuichiro lost his left arm while trying to protect Muichiro. As the Demon badgered them for their worthlessness, Muichiro lost himself in a rage and destroyed the demon with all the tools at their disposal and wooden logs.
By sunrise, the Demon withered into ash and Muichiro dragged himself back to the house. There, he found Yuichiro near death praying to the heavens that his brother might survive. He laid there grasping his brother's hand as he died.