The RG421MSP is an RG series solid body electric guitar model introduced by Ibanez for 2020. It is produced in Indonesia.

The RG421MSP features a meranti body bolted to a maple Wizard III neck with a 24-fret maple fingerboard with black dot position markers. Components include a pair of Ibanez Quantum humbucking pickups with white bobbins, an F106 fixed bridge and Ibanez tuning machines.

For 2021 the body material was changed to poplar and a new Pink Sparkle finish was offered.

The RG421 is a similar model with a jatoba fretboard. The RG421AHM is a similar model with an ash body. The RG470MSP is a model with a similar finish but with a tremolo bridge and a middle single-coil pickup.