Sumirei Ando is a teacher at Jinbou Elementary. She is known to be extremely strict, attacking students for even the simplest mistakes. She has a special dislike of Sana, due to her constant being the exception to the rules. She also disagrees constantly with her boss, Principal Narunaru.

When the school goes on a field trip into the woods, it is discovered she has an insatiable love for the limbo. She cannot stop herself from participating, and removes her clothes to Polynesian style dress and surrounds herself with torches.

When she is directing a school-wide test which may prevent Sana from passing, the faculty and students all protest and beg her to not make the students take it. It is revealed that despite her extreme strictness, she always wanted to be the loved teacher, so she does not make the students take it, instead beginning to limbo again.

She meets Zenjiro by accident when he accidentally called her looking for a blind date on Christmas. Sumirei is stricken immediately, much to Zenjiro's disdain due to his unattraction to her. Eventually, Zenjiro sees that there is no other woman who will date him, and essentially accepts his fate to be with her.