Yagyu Reia, a sacred ninja, has been fighting against the demonic ninja clan. A kendo national champion, she takes action to protect Hayato Izawa. However, Izawa is targeted by the demon ninja female commander, Spider Princess, and falls into their hands. Reia attacks to protect him, but the Spider Princess exploits an opening, causing Izawa to be brainwashed. Despite struggling, Reia transforms into the sacred ninja Reia and knocks Izawa unconscious. Hearing the screams of a new victim, she rushes to the scene—only to find a woman being attacked by the ninja beast Taranchu, but the woman turns out to be the demon ninja Spider Princess herself. Reia takes damage from Spider Princess's assault, is tormented until her transformation is undone, and is ultimately captured.