Lesson 40: Head goes Bakān! The Shock of the Truth

'''Head goes Bakān! The Shock of the Truth''' is the fortieth episode of Engine Sentai Go-Onger.

Plot
While Gou goes looking for him in the woods as they were looking for mushrooms, Jyan finds Suugu playing an ocarina and feels a "Wafu-Wafu" from him. Jyan attempts to befriend him, but Gou arrives and battles Suugu to Jyan's dismay. Gou is shocked to find that Suugu's fighting stance is the same as Dan, a Beast Arts master who both he and Rio learned from in the past. At SCRTC, Xia Fu cannot believe that Dan still lives as he was killed by Rio long ago. However, Long reveals to Rio that he revived Dan as a puppet that would serve only the Gen Jū King, with the masterless Suugu going on a berserk rampage. He overpowers the Jūken giants single-handedly before being defeated by SaiDaiGeki Fire as Rio arrives before the team, revealing that his battle with Dan had not truly ended. On the night Rio was to end his rivalry with him, Dan was already gravely wounded prior to the fight, thus Rio was robbed of a true victory. A dying Dan tells Rio that his true rival is one who will defeat him: Dan's own son, Jyan. Jyan is horrified and confused of this new information as Suugu attempted to kill him. Though the others attempt to keep Suugu from killing his son, Jyan expresses his feelings about family while taking Suugu's beating until Rio emerges in a new form, embracing his destiny as the Gen Jū King. The four Gekirangers battle the Mythical Generals, only to be overpowered by them before Rio blasts them, allowing Jyan time to train for their final confrontation. Rio and his group take their leave, with the war between the Geki Jūken and a fully-powered Gen Jūken beginning as Jyan is now in a state of utter pandemonium.