I found this in amazon jp for cheap-ish (on amazon outlet). I saw this thread and figured it should at least work with libredrive but no other details.
And then there's this thread which has very similar model number, just differ by one letter "PUS" vs "PUV" but the rest seems suspiciously familiar. I went ahead and flashed with 1.03 using SDFtool and the BU-40N 1.03 firmware; the app says it's encrypted firmware hence the 1.03.
One flashing later (using the usb enclosure as is), it seems to be able to read UHD disc (only checked up to content listing in makemkv) and ripped a few blu-ray discs fine. I haven't tested burning yet.
Unfortunately I forgot to take note of the drive info before flasing but here it is after flashing. I think it's almost exactly the same as the one on PUS thread (just differing in serial number and firmware date).
Drive Information
OS device name: F:
Manufacturer: BUFFALO
Product: Optical Drive
Revision: 1.03
Serial number:
Firmware date: 2118-10-24 19:34
Bus encryption flags: 17
Highest AACS version: 82
LibreDrive Information
Status: Enabled
Drive platform: MT1959
Firmware type: Patched (microcode access re-enabled)
Firmware version: 1.03
DVD all regions: Yes
BD raw data read: Yes
BD raw metadata read: Yes
Unrestricted read speed: Yes