The disappointment came after the off-form Thai team went down in straight games to India in the knockout quarter-finals on Friday, which relegated them to 5th-8th places play-offs. Today they will take on Australia for the 7th-8th places.
Thailand finished sixth in the Asian Championship, which earned them a place in the eight-team AVC Cup here.
Japan, the Asian Games champions, were represented by a young squad preparing for the 2016 Olympic Games. Thailand lost the first two games 23-25 24-26, but pulled up their socks to win the next two games 25-23 25-16 for a 2-2 tie.
The tie-breaker saw Thailand, led by powerful hitter Jirayu Raksakaew, took a commanding 9-6 lead before Japan roared back mightily with explosive attacks and solid blocks. The Japanese caught Thailand at 9-9 and stormed on to win the decider 15-11 and the match.
Jirayu Raksakaew scored a match-high 39 points consisting of 35 attack hits, 3 blocks and one serve. Issel Otake led Japan with 21 points.
"We did not play well in the first two games, but found our rhythm in the third and fourth games. We also started confidently in the deciding game, which we led 9-6. Japan worked their services well and our reception was poor. We simply collapsed. It's a pity we could not win. We just let the victory slip through our fingers," Thailand's head coach Monchai Supajirakul said.
Meanwhile, in another play-off match yesterday, title-holders China, who fielded their junior team, brushed off Australia in four dramatic games 25-22 31-33 25-20 25-22.
The semi-finals later yesterday saw India go up against world No 11 Iran and South Korea challenge Kazakhstan, the team they had beaten in straight games in the group round-robin preliminaries.
In the final day of the week-long tournament today, Thailand will play Australia, the team they had beaten in the preliminaries, in the 7th-8th play-off, while Japan will go up against China in the 5th-6th playoff.
The final and the third-place playoff will also be held today, followed by the awards presentation and closing ceremony.