Sumire Saitozaki was the first girl who fell in love with Jokichi Yudasei, the young man who would later become the father of Ayano Aishi.

Sumire was a kind, gentle, and pure-hearted girl who never wished harm upon anyone.

However, after her cruel death at the hands of Ryoba Aishi, she became a restless spirit that was unable to pass on to the afterlife, forever haunting the location where she was killed.

To this day, she lingers in the east third floor girls' restroom, as if she is waiting for an opportunity to enact vengenace upon the woman who took her life.

Recently, the lightbulbs in that bathroom have stopped working, as if her malice has finally grown strong enough to begin affecting the physical world...