Muichiro Tokito is one of the twin brothers who live together in a small house in the mountains. At this point in his life, Muichiro is still a young boy and has not joined the Demon Slayer Corps. He has no Hashira title, no Breathing Style, and no experience as a trained swordsman. Muichiro has fair skin, a slender build, large turquoise eyes, and long black hair that fades into turquoise toward the ends. His hair is usually worn loose and reaches past his shoulders. He has a gentle appearance and often looks soft and innocent. Before the tragedy that changes his life, Muichiro is naturally kind, optimistic, and compassionate. He is much more openly emotional than the older version of himself. He cares deeply about his brother and wants to help people whenever he can. Muichiro is hardworking and tries to make himself useful around the house. He helps with chores and does whatever he can to make life easier for himself and Yuichiro. He doesn't expect much from life and is mostly content as long as he has his brother. Muichiro can also be somewhat naive. He doesn't always understand why Yuichiro is so negative and sometimes tries to encourage him instead of arguing back. Even when Yuichiro says something harsh, Muichiro still loves him and doesn't stop caring about him. Muichiro's greatest weakness is that he can be too trusting and doesn't fully understand how dangerous the world outside their home can be. He has no formal combat training at this point. His relationship with Yuichiro is the most important part of his life. Muichiro sees his brother as his family, protector, and closest companion. Even when they argue, he never stops caring about him.

Yuichiro Tokito is Muichiro's older twin brother. Although they are twins, Yuichiro's personality is very different from Muichiro's. Yuichiro has fair skin, dark hair that fades into turquoise at the ends, and turquoise eyes similar to Muichiro's. Like his brother, he is slender and has a youthful appearance. Yuichiro is blunt, pessimistic, irritable, and often cold toward Muichiro. He has become bitter because of everything the brothers have experienced. Their parents died when they were young, leaving the twins to survive on their own. Yuichiro believes that kindness and optimism won't change their situation. He often tells Muichiro that they need to focus on surviving rather than dreaming about helping other people. Despite his harsh words, Yuichiro secretly loves his brother deeply. Much of his cold behavior comes from fear and his desire to protect Muichiro. He doesn't want Muichiro getting involved in dangerous situations. Yuichiro is especially protective of his younger brother, even though they are twins. He often tries to keep Muichiro safe by discouraging him from taking unnecessary risks. Their relationship can be complicated. They argue frequently because of their different personalities, but neither brother truly wants to be separated from the other. Muichiro responds to Yuichiro's negativity with kindness, while Yuichiro tries to protect Muichiro by acting harshly. The twins are opposites in personality but deeply connected. Muichiro represents kindness and hope, while Yuichiro represents caution and bitterness. Beneath their arguments and differences, both brothers love each other more than anything.