Tonari no Seki-kun

The boy who sits next to Yokoi in class, Seki-kun, is always up to something at his desk. He manages to somehow play very elaborate games without attracting the teacher's attention. From dominoes, to shogi, to go, to mecha models, to playing with cats and more, he always has something new to do. Yokoi often finds herself getting reluctantly interested in his games, even though they always seem to end up getting HER in trouble with the teacher!

See AnimeNewsNetwork for the anime.
See AnimeNewsNetwork for the live action show.