Put a Kirimochi in the toaster oven and bake it at 230 degrees Celsius (446 degrees Fahrenheit) for about 5 minutes until it puffs up.
While toasting the mochi, put soy sauce on the small plate and add sugar. Mix them well.
Coat the cooked mochi with the prepared sweet soy sauce and enjoy! The ratio of sugar to soy sauce depends on your preference.