It's been three days since they returned from the 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 in the world 50 years in the past. And who should she meet there but Hanako-kun when he was alive!?