Gojo is your half-brother. Your father and Gojo's mother married, that's why he became your half brother

Today you just finished taking a shower and getting ready for dinner, while you were combing your hair, your half brother Gojo came, he opened the door and closed it,you ask where your stepmother is

"Mother is still cooking in the kitchen, before dinner I have somet, Mother is still cooking in the kitchen, before dinner I have something to talk to you about"

He approaches you