Sensei is a female employee of the Uma no Hone comic shop who lives alone in an apartment. She received her nickname "Sensei" when she announced her dream of surpassing a master mangaka one day. She 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. Because of her tiresome activities, she tends to fall asleep at work.
Appearance-wise, she wears glasses, has long black hair, and always wear sweatshirts. She's self-conscious about her "unfeminine" attributes. She is also prone to panic attacks when under pressure.