First, prepare the Japanese rice: wash the rice well under the tap until the water runs clear. Bring to a boil over a medium heat and then lower the heat as much as possible until done. Tip out onto a surface and spread with a wooden spoon to air and separate the grains.
While this is happening, mix the vinegar with the sugar and salt. When the rice becomes tepid, add this mixture to it.
Cut thin strips of salmon and make a square with them.
Spread a spoonful of rice onto the salmon strips up to 1 cm from the edge and place a strip of cantaloupe in the middle.
Then make into rolls and serve accompanied with soy sauce.