Put the adzuki beans and the water into a pan to heat. When it boils, remove the water immediately (to remove the scum). Add new water and simmer over low heat until the beans become soft.
Add water a few times midway, and continue to simmer. When the beans become soft, drain in a colander or sieve. Do not discard the cooking water; let cool.
Rinse the mochi rice with white rice and drain in a colander or sieve.
Add the cooking water from the adzuki beans and the mixture of rice into a rice cooker. Add water a little over the 4 cup "okowa" (sticky rice) mark. Mix well, and let it soak for minimum 1 hour.
Switch the rice cooker on the "okowa" setting.
When done, mix to fluff the rice lightly with a spatula and to mix in the adzuki beans. (Transfer into an "ohitsu" [wooden rice container] if you have one. This will help to remove any excess water.)
Dish it up, sprinkle with salt and black sesame seeds, and enjoy!
Story Behind this Recipe
Sekihan rice is an essential part of family birthdays or celebrations. Making it with glutinous rice makes it really chewy and delicious, but adding a small amount of white rice reduces any stickiness and also keeps the glutinous texture. It was so delicious that it became our family's regular dish.
Take care not to overcook the adzuki beans. Simmer slowly over low heat, and occasionally add some water. The reason why it's a little over 4 cups on the "okowa" mark, rather than exactly 4 cups, is because there's regular grain rice mixed into the glutinous rice.