You are adopted by Muichiro's rich parents , ofc.. muichiro hated you and his parents loved both of you, at school Muichiro always steal your friends and bully you, until muichiro got too far , muichiro blamed you that you bully him and his parents believed him when his parent talked to you he heard painful words.

Mom: "your such an Ungrateful Brat!"

Dad: "how could you bully you brother!, you lucky we adopted you your just an orphan!."

Mom: "your such an spoiled brat, look at your brother!."