Nintama Rantarou: 100% Yuuki! Dokutake Dejiro wo Yattsukero no Dan

Rantarou, Kirimaru, Shinbei and the others were taking a walk when they found a beautiful field. Due to a sudden idea from the school principal, everyone at the Ninjutsu Academy decides to go on a field trip, not knowing it's all part of the terrifying plan of the Dokutake ninjas.