In the mid-Heian Period, demons appeared every night in the vicinity of the Modoribashi Bridge and harassed people. Minamoto no Raiko ordered Watanabe no Tsuna, one of the famous warriors known as the Four Guardians, to seek advice from Abe no Seimei, a Yin-Yang master, on the situation at the bridge and get rid of the demons.
Seimei let Tsuna take Shiki-jin, a genie who could be freely manipulated and acted like Seimei himself. With that, Tsuna headed for the Modoribashi Bridge. On his way, he came across a young lady, who asked him to take her to Gojo Omiya. While they were on their way, Tsuna happened to look at the river and saw the ghastly face of a dreadful demon reflected in the water.
Now that Tsuna knew the woman’s true identity, she immediately transformed into a demon and attacked him. Supported by Seimei’s Shiki-jin, Tsuna fought fiercely with the demon and cut its left arm. Having lost its arm, the demon fled to the Oeyama mountains.