The RG521QS is an RG series solid body electric guitar model introduced by Ibanez in 1998. It was a spot model which was produced in Japan by FujiGen. This guitar is believed to have been created as a special model for the Norwegian Ibanez distributor Norsk Musikk AS but was also sold in Germany through Meinl Distribution. The RG521QS was likely produced in small numbers, perhaps 50 or fewer units.
The official name of this model is misleading. While the guitar bears a resemblance to the RG520QS, which was produced in the same timeframe, it's been named RG521QS. A model number ending in "1" would normally have a fixed bridge but since the construction of a non-locking Wilkinson tremolo is closer to a fixed bridge rather than an Edge tremolo Hoshino supposedly decided to go with the RG521 model code.
The RG521QS features a mahogany body with a quilted sapele top bolted to a maple neck with a rosewood fingerboard with dot position markers. Components include dual Ibanez Vintage humbucking pickups, a Wilkinson VS100G synchronized tremolo bridge and Gotoh locking tuning machines.