Toilet-Bound Hanako-Kun Vol. 8 (manga)

Kou has seemed depressed ever since he, Nene, and Hanako-kun returned from the Hell of Mirrors three days prior. To cheer him up, the three friends decide to go to a Tanabata festival held within one of the school's Boundaries. But instead of getting to enjoy the festival with Kou and Hanako-kun, Nene is suddenly whisked off to fifty years in the past--where she finds herself face-to-face with a living Hanako-kun?!