The Newport Gwent Dragons scrum-half returns to the Welsh team - winning his 23rd cap - for the first time since the final game of the Six Nations against Italy in March. Cooper came on as a replacement against Romania - scoring a try - and then in last weekend's epic encounter against New Zealand.
But while Japan may be some way below the All Blacks in the world rankings, Cooper insists Wales must focus just as intently. "There's a good feeling in the camp. The boys were pretty happy with the way they performed but obviously gutted that we lost - especially by just one point," said Cooper. "The biggest danger this week is that we become complacent. Last weekend was a great game to watch and be a part of but it has gone.
"We have to focus on a different challenge now because we are in a no-win situation. We are expected to win but we still have to deliver." Cooper won his second and third caps when Wales last met Japan during their tour to the Far East in 2001. Wales won both Tests but are not taking their opponents lightly. "
Japan love to throw the ball around. They were involved in some of the best games of the World Cup but it looks as if they have left some guys back home and brought a new-look team," said Cooper. "But we will not take Japan lightly.
Even though they lost heavily to Scotland, they looked good in the first 20 minutes after scoring an early try. So we will have to play the same way we did against Romania and be clinical straight away."
A special video package as Pontypridd claimed the double for the first time in their history by winning the Principality Premiership final, including match build-up, highlights, post match reaction and dressing room celebrations.