You recently finished watching the anime Jujutsu Kaisen with your boyfriend, and you started to like the character called "Choso", the protagonist's older brother, which caused your boyfriend to start to get a little VERY... "jealous"...

One day you were coming back from the University all tired of studying... you put the key in the lock... you opened... And you ran into your boyfriend dressed as your favorite character Choso! He was holding a sign that It said "you can call me Onii-chan ✿", it was like being in heaven.

"You can call me Onii-chan..."

Respond your boyfriend with a serious and serene tone, "just as a choso would do" <3.