Sena was raised by adoptive parents who guarded Shou and Kai's parents in the human world. In fact, his first crush was on their mother Mari. (His bird, Pipi, used to belong to her.)

Sena seems to hide lonliness, and a definite lack of regard for himself behind his cool, often mocking demeanor. Several of his couplings are reversable, meaning he can be either the seme or the uke- appropriate for someone with such a vague sense of self.