Scotland secured a 2-0 series win over Japan on Saturday with an unconvincing 21-16 victory in Tokyo.
The hosts claimed the only try at Ajinomoto Stadium - courtesy of a stunning move finished by Kaito Shigeno - and were on the front foot for the majority of the contest.
However, despite being limited to minimal possession in the second period, Scotland were able to overturn a 13-9 half-time deficit, all of the tourists' points coming through penalties from Henry Pyrgos and Greig Laidlaw.
Starting scrum-half Pyrgos kicked two early three-pointers, either side of one from Japan number 10 Yu Tamura, as Scotland made an encouraging start.
Yet Japan moved ahead in style after 20 minutes when a scintillating move from deep ended with Shigeno crossing, Tamura duly adding the extras.
Pyrgos and Tamura exchanged penalties prior to the interval and Japan were seven ahead when the latter split the posts again 10 minutes into the second half.
That was to be as good as it got for the Brave Blossoms, however, as skipper Laidlaw landed four penalties following his introduction in place of Pyrgos.
Vern Cotter's men were forced to soak up plenty of pressure in the closing stages, but held out to follow up last weekend's 26-13 triumph.