1. Cut rice cake in 1 inch cubes and set aside.
2. In a strainer, place azuki beans and rinse well under water.
3. In a bowl, soak azuki bean in water enough to cover the beans, for 2 hours.
4. Strain the beans and discard water.
5. In a large pot, place beans, with water about 1 inch above the beans.
6. Heat the pot and allow water to boil.
7. Drain the beans and discard water.
8. Return bean to the same pot and fill fresh water about 1 inch above the beans.
9. Heat the pot and allow water to boil.
10. As the water boils, add sugar and salt and stir well.
11. Continue to boil for 15 minutes.
12. Turn off the heat, allow bean mixture to cool, cover and refrigerate for 1 hour.
13. Grill the rice cake pieces on a preheated grill for about 3 minutes each side or until the get light brown in color.
14. Serve hot bean soup topped with rice cake.