The Yuzuki Family's Four Sons S01 E03 Something's Bothering Gakuto

Gakuto spends a lot of time with the Kirishimas, but it wasn't always this way. Shortly after their parents' deaths, Hayato tried to handle everything on his own, running home from university every day to be there when Gakuto came home from kindergarten. One day, he noticed Kirishima-san's grim looks.