Keiichi Wakaouji

 ( Wakaōji Keiichi) is Mitsuki's doctor and guardian, Fullmoon's current producer, and former keyboardist of ROUTE: L.

Etymology

 * The name Keiichi means "gemstone" (圭) (kei) and "one" (一) (ichi).
 * Keiichi's surname Wakaouji means "young, immature" (若) (waka) and "prince" (王子) (ouji).

Physical appearance
Wakaoji has golden-brown hair (brown hair in the anime) and eyes of nearly the same color.

Mitsuki Kouyama
Acting both her doctor and (in the anime) surrogate father figure, Wakaouji cares for Mitsuki's well-being in place of her parents making him close enough to confide in about Mitsuki's love for music. He instantly recognized her through likeness as Hazuki's daughter. In the manga this also led to him to recognize Full Moon as Mitsuki which he tried to confirm shortly after meeting as her producer. While Mitsuki lied, which he seemed to accept, he displays clear knowledge of her true identity when he explained her medical condition to Oshige. He nevertheless continued to support her as a competent producer and remained her doctor.

In the anime his responsibility as a surrogate father towards Mitsuki is more preceding than a merely acting as a doctor. He visits her father's grave and made the promise to him to look after her like his own daughter. He follows this up by attending as her parent at school, and has even attempted to improve by learning about girls her age through their popular magazines (with comical parent reactions). This is reciprocated by Mitsuki who casually visits him at the hospital and sees him as the alternate guardian/parent to negotiate with her caretaker grandmother. She also relies on him as a listed legal guardian in other matters that she prefer not to talk with her grandmother about. She has openly stated to him that she would be happy to have him as a father, to which he is touched to hear.

Trivia

 * The author purposely made Wakaouji look like Eichi. She says that Wakaouji's image is that of Eichi as an adult. The two even have the same hairstyle.
 * Dr. Wakaouji mentions that his car is not equipped with a CD player.
 * After Wakaouji decides to be Mitsuki's producer, he now works as a part-time doctor instead of a full-time doctor. In fact, he turned down the offer of becoming the next director of the hospital.
 * In the manga, Wakauoji became Full Moon's producer without knowing that Mitsuki is Full Moon, although when he first met Full Moon, he suspected that Mitsuki was her.