13th Period 'Turn on the Water' / 14th Period 'Dress Up' / 15th Period 'Top and Bottom' / 16th Period 'Surprise Attack'

Following the line of the precedent OVAs (of the same name) This anime goes around the normal lives of some elementary school (5th grade, 2nd class room) kids and their adventures, while turning to teens. Their games, stupid jokes, and the misunderstandings ar...