An OVA bundled with the special edition of the fifth manga volume.

Yokoi-san is trying her best to listen in class, but she can't help but watch as Seki-kun is lining up erasers next to her. Seki-kun! Are those dominoes?!

Whilst Rumi is off school with a cold, Goto observes Seki as he plays a game of paper sumo involving a robot opponent, assuming he had a fight with Rumi.