Toilet-bound Hanako-kun, Vol. 8

Its been three days since they returned from within School Mystery Three, the Hell of Mirrors. To cheer up the depressed Kou, Nene heads to the Boundaries Tanabata festival. She was supposed to be enjoying the festival with Hanako-kun and Kou, but suddenly she finds herself fifty years in the past-and happens to meet the living Hanako-kun there?