.opus files from NIS game Asatsugutori

[NIS_help]

I was able to extract 29 .opus files from the Nippon Ichi Software game Asatsugutori's "sound_bgm.dat" with the "ps_fs_v1.bms" script (after trying many other NIS & Disgaea extractors)

They are unplayable, and I was wondering how to extract them with a proper header?- Looking into HxD, these files seem to have no header but audacity can't read the raw data either. I will provide a sample!

Here is the dat file if it can help! https://mega.nz/file/IUE0XDYI#Rc6iXpPO5-wEZ6iebb25Yq3vGvDuhVN4RZLMWtuop3s

[hibari]

Vgmstream played them after renaming the extension to at9