Nintama Rantarou: Dokutake Onsen no Dan

The Lord of Maitake Castle asks the Ninjutsu Academy Headmaster to accompany him when he sneaks out incognito to visit a dango shop, and Rantarou, Kirimaru and Shinbei tag along for the trip as well. However, it turns out that the shop is actually a Dokutake Castle trap, and they're not the only ones who have been caught.