Professor Tomoe Souichi (土萠創一教授) was Hotaru's father. His body was taken over by evil forces, and he was looking for the heart crystals to revive the Messiah.
In the anime, his voice was done by
Kamiya Akira (神谷明)
[Sailor Moon characters]
(c) Takeuchi Naoko, Koudansha, TV Asahi, Toei Douga