What is the Octopus Card?
I decided to go to Hong Kong. I noticed that my Octopus Card with “八達通 OCTOPUS” written on it, which I had issued when I visited there many years ago, was buried in my travel goods. Octopus Card is like an IC card that can be recharged and used for public transportation in Japan, such as Suica, pasmo, ICOCA, and PiTaPa. I remember Octopus Card was able to use it not only on the subway but also in the city.
I wrote “such as”, but OCTOPUS launched earlier than Suica in Japan. Technically, the same Sony’s Felica was used. JR East implemented Suica a few years later, followed by other railway companies, taking advantage of the prior experience with OCTOPUS.
Checked Balance of Octopus Card
I decided to check the balance of my Octopus Card while I was in Japan before my trip. If I had enough balance in it, I might be able to withdraw less cash. I looked up how to check it and found that I could do it with the smartphone app.
1. Install the OCTOPUS app on the smartphone
Android
iPhone
2. Get the Octopus Card ready. Mine looks like this.
3. Launch the OCTOPUS app. (my smartphone is Android)
4. Tap “Transaction & Balance” in the “OCTOPUS CARD” tab (circled in red). 
5. Hold the Octopus Card over the IC card reader on the smartphone after Tap Octopus Card was displayed at the bottom of the screen. 
6. Balance and usage history should be displayed.
In my case, the following screen appeared. The instructions said that I should go to an MTR Customer Service Center if I want to use my Octopus Card again as the card was inactive. According to this website, it becomes Inactive after 1000 days since the last use. Unfortunately, I could not confirm the balance. After arriving in Hong Kong, I thought I would go to one of the MTR Customer Service Centers.
In addition, I tried using another balance check application that I usually use to check the balance of my IC cards in Japan, but it gave me a message saying that the card could not be read. I could not check the balance as I expected.
Here is the article about when I activated the Octopus Card in Hong Kong.
