One thing that happens once you've lived in Japan for long enough, is that your home continent - in my case Europe - suddenly starts to feel interesting and exciting again. For me, this had the result of me deciding to travel all the way to Portugal - using land transport as much as possible, in order to maximize the experience of our magnificent continent.
The first leg of this journey was by taking "Snälltåget", from Stockholm to Berlin. A trip taking a mere 21 hours. About four of those were spent on a ferry linking Trelleborg in the south of Sweden with the Sassnitz on on the Jasmund peninsula in northern Germany. Once the ferry had arrived, the train took a three hour long break to let it's passenger fall asleep comfortably (and probably also because it wouldn't make much sense to arrive in Berlin at 3 AM). But me and a bunch of new found friends used this break for drinks on the platform instead.
Taking the train between Stockholm and Berlin was an interesting experience that proved to be way more fun than I had expected. However, if you're short on time this way of transportation is hardly anything I would recommend. It takes about 20 times longer than travelling by air, and costs about the same. I would also not recommend anyone with a height of 180 cm or more to do it, as the beds on the train are quite small and not very comfortable for giants like us.
Train tickets can be booked at: http://www.snalltaget.se/en