Hazuki Kouyama

 ( Kōyama Hazuki) was the daughter of Fuzuki Kouyama, the wife of Aoi Koga and the mother of Mitsuki Kouyama.

Etymology

 * The name Hazuki means "leaf" (葉) (ha) and "moon" (月) (tsuki/zuki).
 * Hazuki's surname Kouyama means "god" (神) (kou) and "mountain, hill" (山) (yama).
 * Her married name Koga means "old" (古) (ko) and "elegant, graceful" (雅) (ga).

Physical appearance
Hazuki is a spitting image of Mitsuki Kouyama that it is even painful for Fuzuki Kouyama to look at her (Mitsuki).

Personality and traits
Hazuki was a confident and caring woman who wanted her child to be a girl and name her Mitsuki as she wanted a child who will shine forever just like the moon.

In one episode, Mitsuki Kouyama asked Wakaoji-sensei what her parents were like and Wakaoji said that Mitsuki was a lot like Hazuki. Hazuki was said to try to help out whenever she could and had a very kind heart.

Biography
In the anime, Hazuki said it seems such a waste on the music box and wanted to give the song that the music box was playing a name. She named it "Eternal Snow" and that was how the song came to be. After that, the song became ROUTE: L's signature number and Hazuki and Aoi Koga's feelings touched everyone's hearts.

Like Mitsuki, Hazuki was physically weak and often fell ill. Against the wishes of Fuzuki Kouyama, Hazuki married the musician named Aoi. She ran away from home when she was pregnant with Mitsuki because her mother knew Hazuki's body was weak and Hazuki wouldn't survive giving birth to a child. In the anime, she made very few appearances. She was seen in flashbacks attending Aoi's concert and receiving the music box Mitsuki now has from Aoi. She was carrying a girl and agreed with Takuto Kira that Mitsuki was a perfect name. She rarely appears in the manga, only in a couple of flashbacks.

Death
Hazuki's death are different in the anime and manga:
 * In the anime, she died in childbirth because her body was too weak to withstand labor.
 * In the manga, she died in a car accident right after Mitsuki Kouyama's birth.

Manga

 * We're Both Half-Angels
 * Love and Loneliness
 * The Forbidden Hide and Seek
 * Taiyaki, Contrariness, and Meroko
 * Not Even God Can Stop the Moon
 * If the Little Mermaid Is You

Anime

 * I Want You to Hear It!
 * Takuto and Mitsuki's Disagreement
 * Meroko, All Alone
 * My Message
 * Grandma's Past
 * Izumi's Enticing Offer
 * On the Night of the New Moon
 * I Just Can't Tell Him

Trivia

 * Hazuki came up with the title of the song "Eternal Snow".