The Shirakiin house's daughter, Shirakiin Ririchiyo, who has a complex about being unable to live independently and unprotected, feels the need to move out and live on her own under the condition of residing in the mansion named "Ayakashi Kan." In this mansion, only those who have cleared a very strict examination could reside in it, and for each resident, they are accompanied with one agent of the Secret Service (S.S.). Although Ririchiyo has rejected the company of the S.S., while residing in the mansion she finds out that the agent dedicated to protecting her is actually the Fox Spirit whom she previously rescued.

Note: Youko x Boku SS is serialized in Gangan Joker, a shounen magazine.