Sasa is an ippon-datara, a monopedal cyclops-like demon that lives in mountains. He is Ageha's accomplice that attacked Shizuku, Kaya, and Rinko at Yuto's grandparents' house and was almost killed by Shizuku until he was spared when the latter saw Yuto's Light Ferry ability.

In his second appearance, he assumes a bipedal form with androgynous features. After Rinko took him out to eat ice cream at Café Relish, he stopped the fight between Ageha and Himari at her request. Sasa can summon giant pillars from the sky to crush his opponents, increase his mass at will, and fire energy beams from his eye. It is mentioned by Ageha in the anime that his kind are excellent sword-smiths and as such, can repair and restore broken swords to their original condition and strength.

Sasa's anime incarnation portrays him as bipedal and his gender has been changed to a girl, as his mentioning of him being a boy was omitted. Also, like Ageha, he/she becomes a supporting character following Shuten-dōji and Tama's appearance, and plays a key role in restoring Himari's Yasutsuna by shooting it with his/her eye, something that was originally done by Kuesu in the manga by recreating it through some sort of time magic.