The anime's second season reveals that Yougetsu is actually another one of the Eight Sages, Byakuya (the Sage of Haku, the White Immortal). When Doshuu found Eigetsu, Yougetsu saved the child's life by strengthening his dying soul and granting him twenty more years of life, but after that, Eigetsu himself would die and Yougetsu would live on in his body. Later, Doshū became gravely ill, so that Eigetsu willingly surrendered ten of those years to Yougetsu in order to extend his foster-father's life. When Eigetsu has only one month left to live, Sa province is plagued by an epidemic which he recognizes as the same disease that wiped out his native village. He tells Kōrin about his imminent fate and confessed his feelings to her, then sets out by himself to the affected area in the hope of directly helping some people before his death. But when Eigetsu's life is due to end, Yougetsu decides to go into a deep sleep to let Eigetsu keep living.