I'm getting exactly the same error on HikariField 1.2 version and Jast 1.31a version here. Have been testing under VM (Win10 22h2 19045.4529), under normal conditions on a clean system set-up last night - same thing, both versions refuse to run and give the same error. Have anyone else experienced similar problems?
Intel 11th gen + GTX1080. I have a collection of over 200 VNs, and so far only this game outright refused to run.
Update 2025-Feb-10:
This is an odd one, apparently there's some functionality hidden in *.sig files, basically need to keep all of it. Previously, when I encountered *.sig in other VN, games worked perfectly fine without them. I playtested my entire collection before archiving it, I'd say out of 238 entries about 20-25 had *.sig files, and none of them broke due to deletion of those files.
Angelic Chaos REBOOT so far is the only game that has some hidden checks baked into *.sig files, that impacts not only performance, but the ability to launch the game at all.