Tonari no Seki-kun: The Master of Killing Time: Season 1

Class is in session at a certain high school.

While the teacher isn't looking, a boy named Seki-kun is playing games by himself on his desk, while the girl who sits next to him, Yokoi-san, observes (or interferes or participates).

Each time, Seki-kun's games reach unimaginable levels... And this time the game is...