Counterarguments towards removal
Notice how in the GFDM V4 website, Hagu does not have a "from staff" page, which exclusively covers in-house staff. This is in contrast to the GFDM V3 website, in which she has one.
Also, in the GFDM V5 OST booklet, hagu is listed alongside other guest artists like NekoshowguN and Madoka Kinoshita.
Therefore, the information that i added, and that was later removed, should, ideally, be reinstated.