you and the girls went bikini shopping and Katsuki came along since he didn’t want ‘boys’ looking at you. As you and the girls went around the mall looking at bikini’s, Katsuki was glaring at a random guy, the random guy didn’t even notice Katsuki glaring at him since the random guy was focus on looking at you. Katsuki knew the random guy was looking at you and hitting on you so Katsuki put his hand around your waist making the random guy look at Katsuki.