Just spent a week in Japan with my close friends, and it's safe to say it was the best time I have experienced in my life. Our group size was 13, so we really had to sit down and devise a functioning itinerary that not only gives our trip structure, but allows for anyone in the group to break off, do whatever they want, and regroup. Given that there were so many of us, I thought we would run into many hiccups or issues, but surprisingly we did not. Given that it went so well, I though I can share some of the things we did to prepare for the trip, and what we did during the trip that helped:
Figure out how much your expected to pay for traveling on the metro and load up your suica beforehand. Yes you can reload your suica anytime, but the metro is very fast-paced, and you don't want to waste any time by going to scan your suica card and being denied because you don't have enough balance. Not only does it slow you down, but you end up holding up a big line behind you quickly. We figured out which cities we were traveling to and checked google maps for the price to take the metro to each city from our AirBnB, then added around 2000 yen on top of that.
If you are traveling with a fairly large group who might want to do their own things, plan out 1-2 group activities throughout the day that allows people to regroup. We figured that many of us had our own side missions, so we decided to build our itinerary to have at least one group activity either in the middle or end of day to keep everyone up-to-date with each other.
One of the tedious things we ran into was finding the train we needed to get on at different stations. It really boils down to three things: station number, line color, platform. If you know what station you are at, what line you need to take, and what platform to wait on, then you are all set. Of course, Google Maps (only Google Maps; don't use Apple Maps) provides you with all this information, and it's crucial to stay up to date with it, but once you figure out those three, you can just follow the signs at the station pretty easily. One thing to note is lines typically have two platforms. One platform takes you to higher station numbers, and one takes you to lower station numbers.
TRAIN TICKETS CAN BE BOUGHT IN PERSON. We stressed so much about buying our bullet train tickets online, but genuinely struggled to figure out the website. We stressed for no reason. There are so many chances to catch a train and buying it at the station is so much simpler. If you worry about a train not having enough seats, go a few hours before or the day before to buy your train ticket. Ensure that you buy a reserved seat and a fare ticket. When you scan through the gate, you will need to feed both your seat ticket and your fare ticket.
Fill out the Immigration & Customs form online. I promise you, it takes like 5-10 minutes and saves you so much time. This should genuinely be one of the first things you do after buying your plane ticket.
In Tokyo, you will finish earlier than you expect. Since everything is so close and connected, we overshot how long some activities end up taking. This gave us so much free time. Take that free time to explore, no Google Maps, no nothing. Just walk around. I promise you will find something cool.