Taking the wrong train and the fun times that ensue

There are many different train lines and companies in and around Tokyo. Typically, each train has its own stop on its own platform or on a particular side of one platform so it's very easy to know which train you're getting on in principle.

However, in practice some trains will change into other trains or the line will branch or something else. Generally, the terminal stop is indicated both on the train and on the signs so you should know what you're in for, but sometimes you're not paying attention when you get on the train or you just get really unlucky when a train that you thought would turn into a local train turns into an express.

In general, the best thing to do in this situation is to get off the train as soon as you discover your error and either backtrack or take an alternate route (if you know one). As long as it's not the last train, it isn't necessarily that big of a deal, although taking an alternate route might cost you a bit more, especially if it involves changing to a different train line or company. Also, if you mess up your attempt to backtrack, you might also end up spending more than you planned on.

For example, the other week I was taking the Fukutoshin line (part of the Tokyo Metro system) home from Ikebukuro. This platform has one Fukutoshin train going toward downtown Tokyo and one going further out. A few stops after Ikebukuro on this line, however, this train branches; one line continues to be the Fukutoshin while the other becomes a Seibu-Ikebukuro train or something (owned by Seibu).

I wasn't paying attention and I accidentally got on the express train that was going to turn into a Seibu. I could have got off at the next stop on the express and it would have been fine, but I was reading or playing with my phone or something and didn't notice until the announcement for Nerima started. I know that Nerima is definitely not the right way.

So I got off at Nerima and went onto the platform that I believed should be retracing my steps (also, everyone on the platform stared at me so I suspect that not many foreigners go there), but instead of getting onto the Seibu train that would turn back into a Yurakucho, I got on one that remained a Seibu train until it rolled up to Ikebukuro on a different platform.

So I had to leave at the gate, pay my 440 yen (I had taken a different Tokyo Metro train line to get to Ikebukuro in the first place) and then go back to a train that would take me to my station, paying another 240 to get home (for reference, I can go almost all over Tokyo from my station on 240 yen).

I could have got back on the train going the other way and get on the correct train that would take me to the right platform. However, I was tired and hungry so I just wanted to go home instead of continuing to play train pinball.

Since then, I definitely pay much more attention to the trains before I get on them.