Mikado Ryōko

Ryoko Mikado is the school doctor at Sainan High. She also helps out other extraterrestrials on Earth in various manners, usually those dealing with medical care, though she does offer students a variety of her own concoctions.

Personality
Formerly an operative for a shadowy, black market extraterrestrial organization bent on overthrowing with Emperor Gid, she fled from her superiors to Earth in hopes of hiding her identity. Proof of her non-human origins are the elf-like ears hidden by her short hair, and her extreme weight, though it has not yet been specified what her species is. Furthermore, she seems to be smitten with Rito, shown when she once asked him to rub oil on her at the beach, and didn't look surprised when Rito accidentally says love you to her, Nana, Yui, and Run.