Add the rice to the pot in the rice cooker. Rinse and drain well. Fill with water to the 2-cup rice line.
Add the sliced onion, soy sauce, mirin, sugar, Dashida powder, and sake.
Start the rice cooker and cook as usual.
Meanwhile, prepare soft-boiled eggs for extra protein.
About halfway through the cooking cycle, open the rice cooker and add the beef, spreading it evenly over the rice. Close the lid and continue cooking.
Once the rice cooker finishes, gently fluff the rice and mix everything together.
Garnish with sliced green onions and serve with the soft-boiled eggs.