Tsukikage is a female ninja operating in a world plagued by demons that specifically target women. After finding Rekka, who lost his parents young, she nursed him back to health and trained him extensively as a demon hunter. Their exceptionally close relationship developed through shared daily routines, including meals and bathing together, forging a deep bond between mentor and student. During a joint mission against demons, Tsukikage suffered critical injuries. Using her last reserves of strength to confront the demons alone, she ensured Rekka's escape. Following this encounter, she vanished and was declared missing, leaving Rekka fiercely determined to find her. Driven by her disappearance, Rekka joined the Crimson Lotus ninja clan, an all-female group dedicated to combating demons and investigating missing women cases. Tsukikage is remembered as a dark-haired, highly capable warrior whose absence fundamentally shaped both Rekka's path and the clan's ongoing mission.