sakugawiki presumes Tomioka for the chorus (first cut):
OP：サビ（憶測）

first purple hair girl: Matsutake?

red hand: Koichi Hashimoto?

Atsuko Nozaki was the CD and AD for the OP so basically everything here has her touch but she probably did genga for some of the characters (machine gun girl, whip lady, sword guy?)