Day 1: castle and Nakanoshima
Day 1 is only the castle and Nakanoshima. From Tanimachi 4-chome walk toward Gokuraku Bridge; pick the keep or the history museum. The museum often closes Tuesday — check that day's notice. One dusk stop. Do not continue to Namba.
Day 2: Minami — Kuromon in the morning
Kuromon in the morning; most stalls shut after noon. Walk the covered stretch of Shinsaibashi, and reach Dotonbori only at night. At Namba, lock the exit and walk toward Ebisubashi, about 5–10 minutes. Do not double back to Umeda.
Day 3: USJ or Kaiyukan — pick one
USJ uses JR Universal City — the gate is the park, and you stay inside. Kaiyukan is the Chuo Line to Osakako, then about 5–10 minutes on foot. Do not stack them. Kyoto is another day.