Hi Yamato-san,
Nice BB indeed, and priced appropriately I think. It's not 2015 anymore, and days of getting thru-neck Alembics for less than 10k usd is gone.....
Tax to import from US isn't too bad, 10% sales tax on 60% of the value, so it should be less than 500 usd for the import tax (maybe more, but that was the case when I imported my last bass from UK.)
I think I know which bass in Osaka you're talking about: that one is also very nice, but it is medium scale and not sure you would like the medium scale in small standard body (I have never touched one).
Also, the neck pickup position is close to the neck (less space b/w pickup and neck-end), some people prefer to have more space (thus the current pickup positions? I prefer the old 'less' space), you may want to consider that.
Anyways, both looks stunning..... It's the second best time of the whole Alembic experience (best being playing one...lol). Good Luck!!
Takeo Sonoi