Nazo no Kanojo X: Nazo no Natsu Matsuri

Akira Tsubaki heads to the summer festival with Mikoto Urabe, Kouhei Ueno, and Ayuko Oka, hoping for a rare chance to enjoy an ordinary date. Ueno and Oka soon slip away on their own, leaving Tsubaki and Urabe to wander through the crowded stalls together.

When the two are separated before the fireworks, Tsubaki follows a strange trail in search of Urabe and the red string said to bind lovers. What begins as a romantic festival outing turns into a bizarre test of the unusual bond that only he and Urabe share.