Hi mate, just recheck your pic, it shows 23300-20P05, not what you posted above (-20P050).
You could always buy brand new from amayama but ouch! US519 https://www.amayama.com/en/search?q=23300-20P05.
I don't know how to reverse search to a model, but your number matches an R33 GTST VIN that I have. It has an alternate part number 23300-AA300 which will be a direct fit, and another part number 23300-08U15 for a different "specification"....my non-existent Japanese wont let me work out the difference
Anyway, all that aside, if you are happy to buy from Japan just contact Jesse Streeter and tell him you need a starter motor for an RB25 he'll come up with new and 2nd options for you.