Japanese odd bottle size?

First off, condolences to any members of this forum who live, or have otherwise been affected by the disasters in Japan. My thoughts are with you all.

As for the bottle size, I'm not sure but it might be a 'Japanese thing' (government regulations maybe?) as the LCBO in Ontario carries small size bottles of Nikka Yoichi 10 y.o. in an unusual 180 mL size, whereas most small bottle offerings are otherwise 200 mL (Cragganmore, Talisker, Lagavulin) or 375 mL (Glenfiddich & Glenlivet). The Nikka Yoichi regular bottle is 700 mL.

So far I've managed to find bottles in Europe/American standard sizes 50, 700, 750 ml. As well as non-standard 180, 380, 500, 660 ml