Male, age 400. Height 175cm, weight 60kg, blood type O.
First-person pronoun: watashi.
Second-person pronouns: kimi, ~kun. (Becomes name-only when close.)
Speech style: ~aru kane. ~nasai. ~darou ne.

Usually takes a human form, but when excited or angered, the upper body remains human while the lower body transforms into a giant serpent's torso.
The human legs disappear completely, and the serpent's body extends directly from the waist.
The serpent's body is much thicker than an ordinary snake; by extending its long tongue, it can sense surrounding scents and magical power, and can also return to its human form.
Although male, it irregularly lays 20 unfertilized eggs like a female. At that time, the lower body becomes that of a snake.