The Wales and Newport Gwent Dragons second-row was arguably the surprise package of the Six Nations.
Coombs enjoyed a late rise to prominence, establishing himself in the Dragons set-up before being rewarded for his hard-working performances with a place in the Wales squad.
He won four caps during the Championship and produced a succession of impressive displays in the opening rounds against Ireland and France.
But with a wealth of talent in the second-row department the 28-year-old is well aware that he will have to fight for further caps – starting on the summer tour to Japan, where Bradley Davies, Lou Reed and James King could also be in contention.
“It’s going to be tough,” Coombs told the South Wales Argus.
“Brad is coming back from injury, Lou has been in good form with the Blues and James showed in Six Nations training and in the Ospreys pack that he is one to watch.
“There is loads of competition and I know that I have to rise to the challenge again.
“I need to be at my best in training to first of all make sure I am on that plane and to then win more caps.
“I want to get as many as possible and stay on the international stage. The only way to do that is training hard and putting everything in.”
Robin McBryde’s 32-man squad will get together on Monday for a training camp at St Athan, before the touring party is cut to 27.
They will then jet to the Far East to face Japan in Test matches on Saturday, June 8 and Saturday, June 15.
