Great Britain Under-20s began their U20 World Championship Division II Group A campaign with a 6-3 defeat by Japan Under-20s in Vilnius
Austin Mitchell-King and Jordan Buesa were on target for GB, as was Alex Graham on his 17th birthday.
Japan went ahead when Chikara Hanzawa was given space in front of the net to pick the corner and fire past Will Kerlin (8:10).
Yusaku Ando finished off a well-worked move in front of the net (30:04) to give Japan a two-goal advantage, but GB reduced the deficit 12 seconds later as Mitchell-King danced around two defencemen to score on his backhand (30:16).
Hanzawa tucked the puck in at the near post on the powerplay (35:37) for his second goal of the afternoon as Japan led by two at the second intermission.
Jordan Buesa netted short-side at 46:53 to close the gap, but Japan stretched their lead with powerplay goals from Teruto Nakajima (49:49), Riku Ishida (50:31) and Teppei Ueno (54:49).
Graham produced a neat top-corner finish (58:46) in the closing stages as GB netted a consoltation goal.
Head coach, Martin Grubb, said: “It is a big disappointment to lose the game, especially as we were punished for our own mistakes by a very good Japan team.
“We showed good character to get back into the game at 3-2 and we had the momentum. We then took a silly penalty and it changed the game.
“They scored on the powerplay again and we then showed our frustrations by taking too many penalties. Five-on-five we were fine, but you cannot win a game when you give up so many soft goals.
“We need to learn and learn fast to give ourselves the best chance possible of bouncing back in a positive manner tomorrow.
“We have the ability to do so and we will review the game and make sure we are ready.”
GB are straight back into action tomorrow as they face hosts Lithuania at 7pm (5pm UK time).