1) What does the Japanese government accept as a legal source for the value of inherited US real estate? Just a local (US) tax appraisal? Or something else?
(I've read something online that makes the process sound elaborate and expensive.)
2) Also what is considered the cost basis of the real estate when it is sold and capital gains taxes are calculated? HOPEFULLY NOT THE ORIGINAL PURCHASE PRICE almost 60 years ago.

(In the US the cost basis is the value at the time of death, as long as the property is sold within two years.)
(To clarify I’m a Japanese tax resident, US citizen, inheriting real estate from an American who never set foot in Japan.)