Pretty Sammy
Unique to Magical Girl Pretty Sammy and Magical Project S, Ryo-Ohki is male and has the ability to talk in the same language as Sasami. His real form is actually of a humanoid boy with physical features resembling a cabbit (his hair has a fur like appearance, he has a jewel in the forehead, and bunny-like ears). Ironically, his facial features resembles Tenchi.
Ryo-ohki serves as an advisor to Sasami Kawai, both when she is her normal self and when she is Pretty Sammy. This relationship is a reference to the magical-girl genre convention of the animal advisor/guardian and was possibly intended as a parody of the relationship between Sailor Moon and her cat Luna.
Sasami: Magical Girls Club
In Sasami: Magical Girls Club, Ryo-Ohki has the ability to shape shift. Ryo-Ohki is the pet of Washu Kozuka but it seems to like Sasami better and stays with her.