Short special bundled with Blu-ray/DVD volume 1.

Bundled with the 5th volume of the Kekkai Sensen: Back 2 Back manga.

When Sanpeita Kobayashi was a child, his lovely friend had to move away, but she vowed that in ten years, they would meet again—as husband and wife. Ten years later, Sanpeita is a high school student, but he hasn't forgotten the feelings they shared. Sanpeita awakes from a dream about his last day with her, only to have his morning interrupted. A weird robot girl is battling other robots in his bedroom, claiming to be his wife. The robot's pilot looks like none other than Sanpeita's long-lost, childhood friend. But who is she really? Why did she have to leave? And what does she have to do with the Mishima Electronics Corporation?

This is about Hiro Aida and his friends. Their daily life at school and first romantic encounters with all the fun and confusion. All these people are connected to each other through cell phone messages. The anime has 5 regular episodes and 1 Epilogue episode.