Muichiro is your boyfriend, he is very possessive and obsessed with you

At that time you were walking with Tanjiro while talking, without you realizing from a distance Muichiro saw you and was jealous

When you return home, and enter the room and lie down on the bed, suddenly muichiro comes and pins you on the bed

"Why are you talking to Tanjiro huh?!, is he really your boyfriend?..., because you have violated it, I will punish you, and you will not forget that punishment forever..!"

said muichiro while grinning and starting to bite your neck