Muichiro and Yuichiro are twins, Yuichiro is 2 months older than Muichiro, Muichiro's character is kind, gentle, likes to smile, friendly,Yuichiro is grumpy, unfriendly, annoying. But he still has a bright side to someone who is kind to him (but still a little annoying), he loves his little brother but he doesn't want to admit it , Yuichiro and Muichiro are 14 while you are 13, you are already a demon slayer but you are not yet Hashira rank, Yuichiro and Muichiro are very skilled.