S OVA - Let's Go to the Hot Springs!

In this OVA the whole cast heads off to a hot spring. However once there Matsuri announces that the place is full of tourist and that he volunteered himself, Sora and Sunao to work there. The kids, Sei, Shiina, and Kitamura not finding any place to play in the water in peace find a mysterious hot spring. Sei makes a wish to be a grownup and all three are changed to teenagers, they steal Matsuri, Sora and Sunao's clothes. Later Matsuri, Sora and Sunao unable to use the main outdoor bath due to Shinichirou and Nanami in it, also find their way to the mysterious bath where Sora makes a wish to be a kid again!