He was supposed to avenge his father's death, but... he was trapped in an organization and had sex for a year, and fell into a female investigator.

I became an investigator to avenge my father's death. He was supposed to defeat Kuroda with this technique... Until that day... A year ago I fell into an organizational trap and now serve as Kuroda's sex slave. I couldn't even remember what my mission was...now. I had no choice but to follow in order to live in the present.