Rinse the rice until the water runs mostly clear and drain well.
Add the rice to a rice cooker. Add frozen edamame, salt, dashi powder, rice vinegar, neutral oil, and water up to the 2-cup line. Stir lightly and cook using the regular or quick-cook setting.
While the rice cooks, wash the shiso leaves, pat them dry with a paper towel, remove the stems, roll the leaves together, and slice them thinly.
When the rice is finished cooking, add sesame seeds, shiso, aonori, and bonito flakes, then gently mix using a cutting motion with a rice paddle.
Lightly wet an onigiri mold with water, fill it with rice, and press firmly to shape the onigiri. If you don’t have a mold, shape the rice balls with your hands.
