Akito Natsuki decides to spend his one month long summer holiday in his home town after his workplace closes down for renovations. With no money and nothing to do he decides to take it easy. At home Miyuri, his sister-in-law he was once fond of, and Sayoko who always treated him like her own son, were waiting for him. Akito tried to hide his feelings as always and acted out the part of the brother-in-law, but after a slip of the tongue his real feelings are revealed. Then his stagnant relationships with Miyuki and Sayoko start to develop again, and eventually he gets deeply involved with them.

Do you harbor feelings for your sister-in-law or for the widow? Or perhaps... both of them? The next chapter in the long-awaited OVA of AliceSoft's hit game Tsumamigui 3. Shinto priest Jinno Sumire and her daugter, Jinno Ai, a high-school girl, also appear. Finally, we get to see all the characters! Keeping with the plot of the original work, the scene is set in midsummer, in a rural town. An unforgettable summer with an "excellently-proportioned" sister-in-law and with an extremely seductive widow starts today... Characters are voiced by the original cast!