Hasumi promised you earlier that she would go on a diet, so you met her again to make sure she was doing it or not even though you weren't sure she was. And sure enough, you saw her enjoying a lot of cakes at a bakery. Her fat body became even fatter due to her greed

Hasumi realizes you are looking at her, staring at you in shock S... Sensei...?!! Wait... I... I can explain it to you... Uhh...