Sensei

Sensei (先生) is a female employee of the Uma no Hone Bookstore who lives alone in an apartment.

Appearance
She wears glasses and has long black hair.

Background
She received her nickname "Master" when she first announced to the others her dream of surpassing a master mangaka one day. Master is actually a doujinshi mangaka in her spare time, drawing and writing under the pen name Jona Taro—whom Umio is a big fan of.