One morning, a huge ground painting of the Mona Lisa appears in the schoolyard of Domori High School. A student claims that it is the work of a yokai, and that creates an uproar.
Zekki, the younger brother of Baki, transfers into Nube's class disguised as a human. Zekki's purpose is to free his brother from Nube's left hand.
The battle between Nube and Zekki leads to the breaking of the Baki's seal. Having lost the demon hand, Nube decides to fight Baki without relying on the hand.
