Return the beans to the pot. Add enough water to cover the beans by about 3/4 inch (2 cm). Simmer over medium heat until the surface of the beans is smooth and the wrinkles are gone, then drain the water.

Put the beans back in the pot. Add enough water to cover the beans by about 3/4 inch (2 cm). Simmer gently over low heat until the beans are soft enough to mash easily with your fingers. Be sure to keep the heat low.

Once the beans are soft, add the salt and sugar. Add the sugar in three portions, stirring and simmering for 15 minutes after each addition. Let the soup sit overnight to allow the flavors to blend.

Serve with toasted mochi on top and enjoy!

You can also make oshiruko using prepared sweet red bean paste. See Recipe ID:18811448