Tanaka-kun is Always Listless

Tanaka is a high school boy who sighs (with a hand on his chin), dozes and sleeps just about anytime and anywhere: in classroom, in PE classes, and even after school hours he is too lazy to move. In contrast, his friend Ohta and other classmates around him are quite energetic, despite of their numerous failed attempts to "wake" Tanaka up.

Synopsis from Anime News Network