Umio is the newest employee of the Uma no Hone comic shop—so he doesn't have a descriptive nickname like the others yet. Umi, as most of his friends call him, is a capable illustrator. Because of that talent, he usually helps Sensei with her manga. He is a total nerd and likes the girly game Die Heart.
Appearance-wise, he wears glasses and has black hair. He lives alone in an apartment one train station away from Sensei's apartment.