Since his family name was known to be born from an evil bloodline, Soshi was secluded inside a shrine as a child. A year later at a party, a woman allows him to work for her in her house, where he is to serve a young Kagero for a living. It is revealed that Kagero told Soshi to respond to the letters sent from his fiancée, to which Soshi believed her to be very perceptive. When Kagero showed Soshi who his fiancée was, that being Ririchiyo, Soshi was surprised to see a spoiled rich girl write letters so keenly. During the summer, they continued writing letters to each other, and Soshi realized his feelings for Ririchiyo, but he started to feel guilty for faking Kagero's personality. After hearing that Ririchiyo moved inside the Maison de Ayakashi, that is when he decided to become a Secret Service agent. Ririchiyo already knows that Kagero was not the one who responded to her letters, but she is shocked to find out that Soshi was actually the one who did, which confirmed how Soshi knew so much about her in the first place.