This one is the doozy. Yamamoto's demon self has been asserting itself more and more. They go to their home and meet the head of the clan, Ryuuzuki, his sister Yu, Mikoto and Takeshi's mother, and Yamamoto's master. His master says that Yamamoto is a half-demon, a very rare event. She sealed his demonic side but it has become more powerful and is overcoming the seal. Meanwhile, Yamamoto's aunt, who is a demon, attempts to play with the cast but she kind of fades away. The twins, plus Yu, attempt to create a greater seal by letting themselves get impregnated by Yoma but fail.
Ryuuzuki arrives with seven powerful priests and says he plans to harvest Yamamoto's power, a ritual that would probably kill them. They manage to escape for a time. Then Yu reappears and Yamamoto's demonic self is born through her, creating his own body and making him independent from Yamamoto. Ryuuzuki appears and starts to attack Yamamoto's demon side. Mikoto, citing the fact that it may be a darker side but it is still Yamamoto, stays behind to protect him, causing Yamamoto and Yu to help as well. They are slowly pushed back and eventually Ryuuzuki fires a powerful blast at Yamamoto's darker self which Mikoto takes in his place. It literally tears her in half, leaving behind her top half which wishes for their happiness. Yamamoto freaks out the his master reveals that his father had been sealed within Yamamoto, I think. Anyway, Yamamoto goes full demon, massacres/tortures the priests and Ryuuzuki, and runs off with Mikoto's corpse.
In the epilogue, Takeshi and Kuro close down their branch, going off to search for Yamamoto with her mother and Yamamoto's master. Yamamoto's darker self, aided by Yu, also search for him. And that's how the story ends.
