Umio is the first protagonist of the story. He is also the newest male employee of the Horse's Bone bookstore - so he doesn't yet have a descriptive nickname like the others. Umi, as most of his friends call him, is a capable illustrator. Because of that talent, he is usually the first to lend Master help with her manga. Appearance-wise he wears glasses and has black hair. He lives alone in an apartment one train station away from Master's apartment.