The relationship between Ya and GACKT is: they once formed the band S.K.I.N. together. The band members also include YOSHIKI and SUGIZO. The group formed in 2007, except for the first few live performances, has never had any activities since then, and has not disbanded. They are all busy with solo.

As for the rest, I haven’t heard of any interaction between the two (maybe there are some stories, I don’t know). Both of them once took the visual kei route.

Qingchun is the lead singer of Heimeng and Sads. Ya and Qingchun have collaborated on the same stage. "Headache and Dub Reel Inch 2012.1.13 Live at Nippon Budokan" has been released on DVD. (Again... There is a comic called "The Evolution of Miss Perfect", written by a VR fan. In the appendix of the comic, both Miyabi and Kiyoharu appear. Among them, the appearance of the comic character Kyohei Takano is Kiyoharu and Takeshi. The appearance of the part above is actually elegant)