ついに大杉に雷が落ちる運命の日がやってきた…。大杉の麓にはボス妖怪を封印する祠が建てられている。人々が対決に備える中、おえまは禁断の封印術を使うことを決意する。一方、バートンは壊れたメガネの代わりになるものを探しているうちに、あるものに出会う。そしてついにボス妖怪が妖怪大蛇の姿をとって大杉を襲撃！妖怪と忍者の最終決戦が始まった…。
The fated day in which lightning strikes the Great Cedar has finally come … At the base of the Great Cedar, a shrine to seal the boss yokai is built. As people prepare for the encounter, Oema decides to use her forbidden sealing techniques. Meanwhile, Burton stumbles across something while looking for spare glasses to replace his broken pair. And at last, the boss yokai raids the Grand Cedar by taking the form of a yokai serpent! The final confrontation between Yokai and Ninjas has ignited…
