Thischairsong:
Its original source has eluded me, and AHA Music's Song Finder didn't help. Does anybody know what this song's original source is? The fact that the file can seamlessly loop strongly implies that it was originally from a video game or a visual novel.
For reference, this MP3 presumably has been re-encoded from a different format used by the original source (likely OGG vorbis or some proprietary ADPCM format).
Therefore, if the source you know of just matches this MP3 exactly in terms of file size and bit rate and such, then that's likely not the true original source and Gilgamesh would be disappointed (but you're still welcome to share your information and I can look into it).
EDIT: The goal is to find a higher-fidelity copy of this song, so a "similar-sounding different song" isn't going to cut it Deathhappens.