Yumiko is an avid shopper and karaoke participant who acts as an older sister figure to the children in her group. Hachiman likens her to an animal queen or fierce predator in the jungle who not only enforces but cares for those within her boundaries – hissing away at those outside them if necessary – yet can also display more emotion by crying during Chiba Community Summer Camp. Although harsh at first, Yumiko eventually shows she has more depth as evidenced by tears being shed during this camp event.