The only J2M2 kit ever released was the one by Hasegawa. It's in 1/32 and came out in July 2012 as a limited edition; code 08227.
The kit offers options for two versions, one without the oil cooler intake and decals for the "ヨC-104" (YOC-104) "Raiden" and another with the the intake and markings for the "ヨD-147" (YOD-147). More about the latter tomorrow.
The decals with the instruction booklet.