Boil azuki beans in large pot for 5 minutes. Drain and rinse and put back in pot.
Add the 6 cups of water and the salt to azuki beans and bring to a boil. Boil for 2 hours or until beans are soft, occasionally skimming the scum on the top. (This scum can make it bitter so try to remove as much as possible.
While the beans are cooking, prepare the mochi.
Put the glutinous rice flour and granulated sugar in a bowl, add water slowly to flour and knead it. Add water until the dough is soft, but still holds its shape.
Form the dough into ping pong sized balls.
Boil water in another pot and put dough balls into the boiling water and reduce to gentle boil. Mochi is done when it floats to the top. Set aside the mochi until the soup is ready.
After the beans are soft, add the vanilla and crystallised sugar according to your taste. Cook for another 15 minutes or until the sugar is dissolved, and the beans are flavoured.
Put the mochi in a bowl and cover with the bean soup.