It seems that ancient was already a general tag before you changed it into an artist tag. Seems that you're going to have to add a unique identifier to the name and change the ancient tag back to general.
Wonder what it'd be though, this is my first time seeing this artist. Maybe ancient_(alerthangar) since that's his twitter username?
Mitsubishi F-2A 13-8515 (c/n M1015) of JASDF 6th TFS, 8th Air Wing, painted in a notional F-16 (or really, if you go far back enough, Egyptian F-4E) style "hill grey" camouflage scheme. Tail code FZ comes from the last two letters of the ICAO code RJFZ for Tsuiki Air Base, the 8th Air Wing's home base.
(Except for those in Okinawa Prefecture, which use RO, the first two ICAO code letters of almost every airport in Japan are RJ. These two [1][2] use RO, though.)