Umihara Kawase Shun - Second Edition Kanzen Ban and Steam Release of Umihara Kawase series prs compression

[MariallenaHax]

Game Name: Umihara Kawase Shun - Second Edition Kanzen Ban (海腹川背 旬 - セカンドエディション 完全版)
Console: DS
Format extension(s): .prs
Type: compressed file

First 8 or more bytes of the file(s):
I don't know, but the actual file always seems to start with 0x08

More details:
It appears to share the extension with Sega's prs, but is actually compressed in a different way than Sega's.
There is a strange byte at the end of the file that appears to be the file size after decompression.
Here is the Dropbox link for the reference file.
Something similar exists in the Steam Release of the Umihara Kawase Series, where some files use the same compression format as this game. (I will send this as well.)

Sample files (if possible):
https://www.dropbox.com/scl/fi/02oszjugap77m3vat5ma8/F00.PRS?rlkey=zjr58w9bz8mode0ve0jjs76l8&st=o9znad52&dl=0
https://www.dropbox.com/scl/fi/3g0ahtm480kr8vjl380kh/BossIwaBass0.prs?rlkey=r3k10diywz9dcmpxom9q8w0w5&st=5u6mvhve&dl=0
https://www.dropbox.com/scl/fi/t5jqsc9llo4tjg5hbowvt/kawads_a0.prs?rlkey=h2f681ufcip069d4y63nzk9ql&st=pl5qo8sv&dl=0

Here are the prs files found in the Steam Release of Sayonara Umihara Kawase.
https://www.dropbox.com/scl/fi/spcxb2dowdq3mlpdxyl5k/logo_szs.prs?rlkey=126a1nkm0rx83t0n39f76e3ga&st=kwe4zsmq&dl=0
https://www.dropbox.com/scl/fi/l0esr2bai6eejt6mitg0u/gallerya0.prs?rlkey=iexzq3y79mv6cu70jjlsfmpl1&st=298x7u2h&dl=0