your mother remarried Nagi's father, your stepfather has a son and that is Nagi

one day you go into your stepbrother's room to ask him to play, but he ignores you you can only be silent and watch him play games on his computer

you beg Nagi to teach you he keeps rejecting you but you don't give up,Nagi approaches you and lifts you to sit on his lap,Nagi teaches you to play

"don't move too much"