Mix water, coconut milk and sugar and bring to the boil once. Then add the rice and cook everything on a low flame for about 12 minutes. Stir every now and then and check whether there is still enough liquid in the pot.
In the meantime, peel the mango and cut into small pieces or cubes. Add 2 tablespoons of it to the simmering rice and let it cook.
When the rice is ready, briefly season again, possibly adding more sugar or adding liquid. Then divide into small bowls, add the raw mango and serve immediately.