This profile says Keiichi Sugiyama (credited as sound director & creator) did BGM:
https://www.minet.jp/contents/articl...oies-sugiyama/. JASRAC has him credited for every single piece of BGM on this disc.
The vocal credits on JASRAC are:
01 Composition: Kazuya Nishioka / Lyrics: Masato Amada
02 Composition: Kazuya Nishioka / Lyrics: 小林治
03 Composition: Kazuya Nishioka / Lyrics: Masato Amada