Keita and the others go into the hills to do a tree planting, but they can only talk about their favorite new anime Professor Renkon. When they find a mystery, they begin to try to solve what has happened just as Professor Renkon would. Meanwhile, Jibanyan and Whisper believe a Yo-Kai is involved and plan to discover it on their own.
景太一行人參加植樹活動，當晚到山中一間酒店留宿，但酒店內竟莫名其妙地四處開花，頭上開花的人更會失控起舞。眼見身邊的人全數淪陷，景太扮成偵探蓮藕教授，決意把幕後黑手揪出來。
