Pound chicken breasts to an even thickness for even cooking. Season with salt, pepper, and garlic powder.
Set up a breading station: place flour in one dish, beaten eggs in another, and panko breadcrumbs in a third.
Dredge each chicken breast in flour, dip in egg, then coat with panko, pressing lightly to adhere.
Heat oil in a pan over medium heat (induction level 5–6). Fry chicken for 3–4 minutes per side until golden brown and cooked through (internal temp 75°C / 165°F). Alternatively, air fry at 375°F (190°C) or bake at 400°F (200°C) for 15-20 minutes, flipping halfway.
Let the chicken rest for a couple of minutes before slicing into strips.
For sides, cook rice (stovetop, rice cooker, or microwave), fluff, and sprinkle with furikake. Thinly slice red cabbage, toss with rice vinegar (and optional sugar/salt), and let it sit for 10-15 minutes. Blanch broccoli in boiling salted water for 1-2 minutes, then cool in an ice bath. Toss with sesame oil and sesame seeds.
Assemble the bento box: place rice with furikake in one section, add sliced chicken katsu beside or on top, steamed broccoli, pickled cabbage, and cherry tomatoes. Drizzle tonkatsu sauce over the chicken or serve it on the side. Enjoy warm or refrigerate and bring to room temperature before eating.