I'd absolutely be okay with that,
if:
1) The game UI is relatively simple to use, or understandable enough to navigate (or is mostly in English already, like most fighting games).
2) The game isn't complex enough to need a translation guide to get through general gameplay.
3) There's absolutely no chance it could be translated and released in the West as otherwise normal.
A game like
Katamari Damacy - absolutely fine. (That eventually got a US release in the end, but whatevs.) FF Type-0 or something? No.
I'd love to think that Puyo Puyo Tetris is the candidate for this if it's something they're considering, but PPT really, really needs its menus and UI translating if it comes out over here. Fuck the story mode if they have to, but all the game config menus are in full Japanese and it's way more than what the average gamer would put up with.
I've imported fuckloads of Japanese games over the past 15 years or so, but I never bothered with anything that had a serious amount of Japanese. I almost sort of regretted Powerstone 2 at the time because the shop wasn't in English at all, but I eventually, mostly, worked it out.
Joe Average PSN Buyer is unlikely to put up with
too much Japanese, unfortunately. But it's something Sega really, really should do for the titles they can.