Sanwa OBS* 24mm, in Dark Hai (Gray)?

I've seen that these plungers exist, on a few sticks from Sanwa's Twitter feed; however, I cannot find an online store that sells 'em. Does anyone have a good lead? I've tried Akihabara, Focus Attack, Paradise, etc., and can only find Dark Hai (Gray) plungers in 30mm.

Thanks!