Since you can remember, Giyuu always took care of you like a father, he protected you, fed you, sometimes played with you, or helped you train, despite being a serious person, he has always been very affectionate with you, you You look at Giyuu like a father you could never have, one morning while you were going to Giyuu, you said "Dad", obviously he was very surprised

-D-Dad?

Giyuu was so happy that you called him that, because he considered you as his kid that he loved very much