Wales' wretched losing run was extended to 18 matches as they conceded 17 unanswered second-half points to lose 24-19 against Japan.
After losing Ben Carter to injury in the opening minute of the contest, Matt Sherratt's side got themselves into a strong position at the Mikuni World Stadium.
Tries from Ben Thomas and Tom Rogers came either side of a penalty try, with Takuro Matsunaga scoring the only try of the first-half for the hosts.
But having led 19-7 at half-time in the searing Kitakyushu heat, Eddie Jones' side put Wales through the ringer and produced an impressive comeback to inflict further pain on those in red.
Tries from Ichigo Nakakusu and Halatoa Vailea and a further seven points from the boot of Matsunaga earned the Brave Blossoms a dramatic victory.
And Wales captain Dewi Lake says his side need to look at themselves after wilting in the Japanese head.
"Probably just ill-discipline for us," he told BBC Scrum V in his post-match interview.
"Whether that be penalty count, or not taking opportunities in the 22, a couple of mistakes cost us dearly, especially in the second-half.
"We just allowed Japan to play their game in the second-half, and they're tough to stop when they're playing at speed.
"Obviously conditions are going to play a factor, but we're not blaming that, again we weren't clinical enough. Obviously the weather was a factor but we'll look at ourselves first."
The damaging defeat means Wales have fallen below Japan and Samoa to a new low of 14th place in the world rankings.
The second Test against Japan takes place in Kobe on Saturday, July 12.
READ MORE: 'Exceptional' Jac Morgan Lauded As Welshman Makes Australia Test Claim With Stellar Lions Showing
