Who rides Metro, who rides JR
One north–south city day with few rides: Midosuji plus ICOCA is enough. Kyobashi, Tsuruhashi or Osaka Castle Park: switch to the JR Loop. A Metro day pass is Metro only. The Loop is a separate fare.
Private railways ignore a Metro day pass
Hankyu for Kawaramachi, Kintetsu for Nara, Nankai for Kansai Airport, Keihan east of Yodoyabashi. ICOCA usually taps local trains. Limited express is extra — check that day's notice. Do not tap a Metro day pass on these gates.
Read the company name before you exit
Namba has three paid areas: Nankai, Kintetsu and Metro. Umeda has JR, Hankyu, Hanshin and three metro lines. The wrong gate means another ticket. Lock the line, then the exit. Last trains are around midnight — trust the board.