Japan's Kei Nishikori handled Ivan Dodig 7-5, 7-6 (7-4), 6-3 in Sunday's first reverse singles rubber to level the best-of-five tie at 2-all, but the 6-foot-10 Karlovic won in a tiebreak in the first set, then cruised through the next two stanzas in a 7-6 (7-4), 6-1, 6-4 defeat of Soeda in the fifth and deciding bout. The big-serving Karlovic smacked 17 aces on the indoor hardcourt at Bourbon Beans Dome.
The two countries split Friday's opening singles when Soeda and Karlovic posted wins in Hyogo, and Croatia, captained by Zeljko Krajan, took the doubles match on Saturday behind Karlovic and Dodig.
This was the first-ever Davis Cup meeting between these two nations.
Croatia captured its lone Davis Cup title in 2005, while Japan has only ever reached one final, and that resulted in a loss against the 32-time champion United States way back in 1921.