A few things that are good to know before you take off.
SAS flies nonstop to from Copenhagen to Tokyo Narita Airport, one of Tokyos two main airports. Flight time is about 10-11 hours. A train is available from Narita, taking you to the center of Tokyo in about an hour. It is by far the quickest, easiest and cheapest way to get there. Keep in mind that Tokyo is one of the most clean cities in the world, which means the train ride is one of the more pleasant ones, seats are even reserved for you when you buy your ticket.
Admitted, I’m more comfortable when wifi is near. Free wifi is hard to find in Tokyo, but luckily they have an even better solution for you: pocket wifi. It’s smaller than your iPhone, you can take it anywhere you go and surf as much as you want – you only have to worry about the battery running out. I ordered it online (from here), got it delivered to the hotel a few days before arrival, wified my way through Tokyo and sent it back with the envelope enclosed. Not only did it keep my Instagram-feed happy, it also helped me get around Tokyos quite hard to navigate-streets. Oh, and about the battery? Nothing an extra charger can’t take care of, and of course it works for both the pocket wifi and your phone. I have this one.