青いぜ!!春

"No one knows the reason behind the cold sweat dripping from his face."

An utterly ordinary middle school, during an utterly ordinary class. It’s the fourth period just before lunch break, and almost none of the students have any focus left. Yet among them, one boy stands out as especially absent-minded: Nobuo Ōyama. He’s suffering from a brutal stomachache, desperately holding back something that absolutely must not come out here and now.