Kobayashi Azusa was one of the original three members of Country Musume in 1999.
She was only a member of the group for their first single, Futari no Hokkaido. After the death of fellow member Yanagihara Hiromi, Kobayashi left Country Musume because the pain of the loss was too great.
After leaving Country Musume, Kobayashi has since worked as a model and actress. She also does cosplay modeling, and has been performing at small venues, away from the main spotlight, since 2008.
In 2013 she released her debut album and also started her work as a producer of idol groups.
Kobayashi Azusa started out working as a model at the age of 15, signed to Junes acting and modeling. She got her first jobs in 1994 and appeared in several gravure magazines and gravure commercials.
At the age of 21, she signed up for an audition held by Tsunku and Tanaka Yoshitake (Country Musume's original producer). Nine girls went through voice and dance lessons at a farm in Hokkaido, and three girls ended up being chosen, Kobayashi being one of them. As the oldest member she became the leader of the group.
A few days before the release of their first single, Yanagihara Hiromi died in a car accident. The group still released their debut single, but Kobayashi left only a month after alledgedly because the pain of the loss of Hiromi was to great. (The real reason might be that she was fired because picture of adult nature of her had surfaced).
A month after her departure she released again 4, an adult photobook, under the name Morita Hiromi. Around the same time, Hello! Project held a concert, where Toda Rinne performed as the only remaining member of the group. She read there Kobayashi's farewell letter, which said:
"Dear Fans, I would like to sincerely thank you for supporting us till this day. Despite how short it has been, I still would like to thank you from the bottom of my heart. Three of us were supposed to start a new group with high hopes and dreams. However, my dearest and best friend, Hiromi, lost her life suddenly and that took heavy mental toll on me. I'd like to apologize to my fans as well as my staff for my weakness in times when I need to be stronger, and all the trouble this may have caused. And once again, thank you very much for your support. Sincerely, Azusa Kobayashi."
In 2000 she became a talento, changing her name to Hayashi Karin (but has as of 2012 changed it back to Kobayashi Azusa). She now works as a model and actress, doing live singing performances and also cosplay modeling and running her own site.
In 2013 she released her first mini-album, entitled "Distance". She said in an interview: "Usually, I am not so great with carrying conversations and expressing my feelings, so I wrote the lyrics as if I was jotting down my inner thoughts and ideas on a notebook. [...] Five years of my thoughts, feelings, and histories are neatly packed in this album." 
She also started producing her first group, PalmSugar.
A year later she released her second album, as well as the news of being the producer of the idol group AISHING FAIRY. She also revelaed that she was producing a group called Mysterious Roses, where she is one of the members.
- [2013.09.25] Distance
- [2014.10.04] Alexandrite
- [2017.02.14] Blue ~Hikari to Yami no Naka de~ (Blue ～光と闇の中で～)
- [2015.11.18] My daughter