Sanae Kise is a third-year student at Umineko Shōgyō High School. She co-founded the school's swimming club alongside her childhood friend, Momoko Orizuka. As a founder, she actively recruited members; claims suggest she brought in Masa Ikariya primarily to meet the minimum membership requirement, though the accuracy of this remains uncertain due to her tendency to fabricate stories.

Sanae exhibits a mischievous personality, frequently creating trouble for others. She spreads rumors or invented narratives to tease club members, often to attract male attention or gain social advantage, contributing to her reputation as an instigator. She also demonstrates a flirtatious demeanor, actively seeking interactions with attractive boys and leveraging her charm for personal benefit.

As a swimmer, Sanae focuses on breaststroke events and possesses notable athletic ability. Her physical characteristics include brown eyes and hair styled with a distinctive ahoge. She stands 170 cm tall with measurements of 79-56-82 cm.