A younger sister had a fight with her mother and ran away from home. The cause of the fight was my younger sister's boyfriend... I was able to stay the night with mixed feelings. The brother and sister slept on a mattress while worrying about the defenseless appearance of the younger sister calmly changing clothes in front of her brother. My brother couldn't perceive it, and he was alone in pain... Until recently, he couldn't control his delusions and jealousy towards his boyfriend who liked to play with the body of his younger sister who he thought was a child.