They also served.

Today there will be a moving ceremony several miles offshore from Sydney's northern beaches. Representatives of the Royal Australian Navy, the Japanese Imperial navy and relatives of two Japanese submariners who perished in midget submarine M 24 sixty-five years ago will participate in a wreath laying and remembrance ceremony.
On May 31, 1942 three Japanese midget submarines managed to penetrate Sydney harbour with the intention of torpedoing the battle cruiser USS Chicago. They were discovered and in the resulting return of fire M 24 fired her torpedoes - which hit the moored ferry HMAS Kuttabul, resulting in the death of twenty one Australian sailors.
Two of the Japanese submarines were sunk and M 24 disappeared, discovered in recent years laying on the ocean floor several miles out to sea off the northern beaches. The wreck has been declared a war grave and presumably contains the remains of it's crew - Sub Lieutenant Katsuhisa Ban and Petty Officer Mamora Ashibe.
The remembrance ceremony will constitute full naval honours from both sides of the former enemy navies - with recognition that this war grave contains the remains of brave men - who also served their countries.
It is also a requiem to the folly of war. The days of barbaric conflict have passed and it seems ironic that the former enemies are now friends. Japan is one of our main trading partners, we buy Japanese cars and tourists from the land of Mount Fuji tour this country as welcome guests.
It is a reminder that the hatred that goes with war is a temporary state of mind - and something that may one day be banned forever !