Mysterious Girlfriend X: A Mysterious Summer Festival

Akira Tsubaki regularly has unusual dreams filled with images he cannot explain, which he dismisses as an oddity with no bearing on real life. One day a new student, Mikoto Urabe, transfers into his class. She stays aloof and avoids talking to anyone, which piques the interest of most of her classmates. By chance, Akira finds her asleep at her desk and carelessly tastes her drool, which triggers a strange reaction that binds the two of them together.

From then on, a connection forms between them that shows itself in emotional responses impossible to hide, and Akira tries to understand the nature of this strange effect. Mikoto explains that she can convey her feelings through her saliva, and this becomes the reason for their daily meetings, since Akira is the only one who reacts this way.

This OVA, released with the ninth volume of the manga, depicts the day Tsubaki goes to the summer festival with Urabe and their friends Ueno and Oka. Akira hopes to spend the festival with Mikoto and grow closer to her, and she agrees, though she remains cautious, wary of attention from their classmates.