to place international calls from Japan a carrier access code is also needed UNLESS you subscribe to a dedicated international plan; the carrier code is dialed before 010
the most used carrier access codes are: KDDI 001, SoftBank Telecom 0061, NTT Communications 0033
Area codes & number examples
Location
Dialing format
Or using +
All areas
010 1 xxx xxx xxxx
+1 xxx xxx xxxx
More info:
Area code locator - Find the area code for a US city or browse codes to see their locations