After their search for the missing Great Priestess Lys leads Rin and Aghyr into trouble and an unexpected battle at the Water Sanctuary, they take some time to regroup among their friends of the Kaishin Clan. There, they meet up with the Fire Oracles Kara and Koru, who have prophesied the arrival of the Scarlet Soulnone other than Rin Shirano herself. With the Fire Oracles' help, Rin reclaims her sister's sword Hitaken, which has chosen her as its wielder. Whether she feels ready to take on the responsibility or not, she is the only one who can carry the ancient exorcist blade now.