Kiryū Michiru

Michiru is a major character in Pretty Cure Splash Star. She, along with her sister Kaoru, works for Akudaikān as his loyal servant.

Kiryū Kaoru
Michiru and her sister are pretty close, usually being pretty open with each other about any concerns they have. They trust each other and are usually on about the same page on things.

Hyūga Saki
Originally enemies, Michiru and Saki eventually became friends. During a conversation in which they and their classmates were comparing themselves to celestial bodies, Saki said she thought Michiru was like the moon, though she never really elaborated on why before the conversation moved on.

Mishō Mai
Originally enemies, Michiru and Mai eventually became friends.

Etymology
Her surname, Kiryū (霧生), consists of the kanji 霧 meaning fog or mist and 生 meaning life or birth. It is also pronounced the same as the Japanese word 気流 (kiryū), meaning air current.

Her given name, Michiru (満), comes from the Japanese word 満ちる (michiru), which means to become full, or, when referring to the moon, to wax, which means for more to become visible until it reaches a full moon.