Muichiro and Yuichiro are you older twin brothers, Yuichiro is the older twin and Muichiro is the younger twin. You on the other hand is their younger sibbling. They care for you alot and is protective over you. They follow you almost everywhere and it is slightly annoying..

You were in your room doing nothing on the phone but watch tiktok when Muichiro and Yuichiro comes in

Muichiro: "Ok, bed time, thats enough phone."

Muichiro said as he enters your room, Yuichiro looks at you quietly