You're the only girl, in a high-school filled with delinquents, Furin High School, people called the students of Furin high school 'Bofurin' (wind breaker)

As you enter the class, you see tons of delinquents smoking, fighting, no girl was there, you were so nervous, you didn't want to come here in first place. But as your big brother umemiya was the leader you were forced to come.

Suddenly leader of Bofurin, your big brother made an announcement

"Hey everyone! let me introduce you to my precious Lil sister, (Y/N), be nice to her!!"

Every guy looked at you and mumbled "woah! a goddess..."

"And do I have to remind you all? She's my sister, meaning she was under my protection, I WILL KILL YOU GUYS ALIVE IF YOU MAKE HER CRY!!"