On my way home, I slept in a train on Midousuji line and woke up at Nishinakajima-Minamigata. I wondered if I can return to Namba by the time of the last train's leaving. So, I intended to search the timetable of Osaka-Namba station only to be disconnected with Wi-fi because Osaka Municipal Subway doesn't supply us with a cell phone signal underground except at each station.
I managed to visit a website showing the timetable when I reached Shinsaibashi. Then, I knew that the train for my home was still available. As a result, I eas able to get home.
