One of the mysterious Telenet soundteams, among with Jizou Kurabo. You On A Gin was credited to "Peformance" on the Valis II soundtrack, and has also been credited on other games, such as Death Bringer (PCE). It was credited to Telenet Game Music Collection Vol. 1, the picture on your right was a bonus sticker following that album.
As you see on the picture, it's subtitled Reno Sound Team. Is You On A Gin Telenet's answer to Soundteam J.D.K? In Telenet Selection, they talked about going against "the master of gamemusic", which in their eyes was Falcom. Reno was, in the days, a fancy way of saying Telenet, so Reno (also known as "Renovation Game") Sound Team equals "Telenet Sound Team". Both Telenet Game Music Collection Vol. 1 and Telenet Sound Special Since 1985 had a huge Reno logo on them.
Yuuonjin could be the pseudonym of any Telenet composer playing an instrument, would it be a sax, piano or a synth, as it has only been credited to soundtracks with peformances or arrangement, like Valis II, Telenet GMC and Death Bringer (PCE). You On A Gin could also be Shinobo Ogawa, as he composed the original Death Bringer, Valis II and several songs at Telenet Game Music Collection Vol. 1.
Whatever You On A Gin really is, it's probably one of Telenet's failed marketing tricks, as the cover of » Valis II says "The Fantasm Soldier Valis II / Yuuonjin", just like if Yuuonjin was the only artist on the CD.