輪廻月姫 (Rinne Tsukihime) is an officially licensed Windows program made by inside-cap/ 帽子屋インサイド that allows you to convert your PC copy of tsukihime into a Gameboy Advance rom.
This is NOT the "輪廻月姫 Box Editon" version of rinne tsukihime
The developers would later create a security/ DRM mechanism that would be added to latter quality-of-life updates for the program.
But, luckily a guy named Karmic64 release a tool on github called "higurashi-gba-hacktools" that can crack the DRM, so that you can play using emulators hasle-free.
Download for the Rinne Tsukihime windows program that used to create the rom
Download for the GBA rom contains both the latest quality-of-life feature, but without the DRM 👍
EDIT: Due to an Anonymous dotation by another fellow Intent archivist we now have the Updated Box Edition of Rinne Tsukihime is now available to the general public
Download for the Rinne Tsukihime Box Edition windows program that used to create the rom
Download for the pre-patched GBA rom contains the latest v5 update, but without the DRM