- Name: Hiroki Koga (古賀博樹)
- Favorite texture: Elastic
- Disliked texture: Puffy
- Favorite taste: Fussy and heavy
- Disliked taste: Sour
- Favorite condition: Being a prisoner of sleepiness
- Disliked condition: Having a full stomach
Hiroki Koga has been with BEMANI since near the very beginning, starting off as a sound data anaylzer in beatmania 2ndMIX back in 1998. In addition to doing notecharts for both beatmania and the early beatmania IIDX games, Hiroki was also the sound director of the first two KEYBOARDMANIA games (a position that Seiya Murai filled in for the third and final game).
Starting with pop'n music 4, Hiroki also started contributing to the pop'n music series, which he has worked on near exclusively after KEYBOARDMANIA 2ndMIX, writing music for the series up until 17 THE MOVIE (with the exception of 8, though he did みなしごハッチ's notecharts). He also provided the soundtrack for QUIZ MAGIC ACADEMY IV and V, as well as Busou Shinki Battle Rondo and OTOMEDIUS.
Hiroki's music tended to be instrumental, with a more full, orchestral sound than most other BEMANI artists, often containing several real instruments in his tracks. He also extensively worked in jazz and rock songs during his tenure, too.
Not unlike Asaki, Hiroki Koga is a very reclusive person. No widely known pictures of him exist on the Internet, he almost never appeared in any BEMANI events, and he's barely ever given any interviews.
Hiroki Koga left KONAMI around 2011-12. His most recent known music for KONAMI was for the first two Tenkaichi Shogi Association (天下一将棋会) games in 2010 and 2011 respectively. He was also listed recently under Special Thanks in 2017's Super Bomberman R (スーパーボンバーマンR).
- ナヤ～ン / Naya~n
- Blue & Green
- ensemble futuro
- Naya~n Jr.
- St. Naya~n
- ナヤ～ン & His Orchestra
- Ritter (with Kozo Nakamura)