Koko's Secret Sashi, the adopted younger brother of Tosan Yaya and her sisters, who was enticed by the boss of the black fox spirits, has returned to destroy Tosan. He comes aided by a giant man with incredible powers packed into his fists and the fearsome Nightmare Fox to attack the fox spirits. Obsessed with his adoptive sister, Yaya, he has come to finally make her acknowledge him by destroying the ones she loves the most, Koko and Gessho. He reveals to Yaya that he knows about Koko's secret, one that even she doesn't know about that has scarred her older sister to her very core.