Tokyo is the largest and most populous city in the world.
The sights are spread out but the public transportation system in Tokyo is amazing, efficient and runs on time. Plus all the signs and announcements are in both Japanese and English.
What hasn't been mentioned, and needs to be, are the local customs and unwritten rules. Learn them.
Here's an article with some but do a search to understand more:
https://www.jrailpass.com/blog/japanese-etiquette-tips
Here are a few:
--no tipping. It's just not done.
--be prepared to take your shoes off a lot. If you are someplace where your shoes are left at the door, and you need to use the restroom, you will find toilet slippers to wear so your socks don't get dirty.
--Get a Suica card. It's used to pay for transportation but can also be used to pay at some stores (convenience stores) and vending machines.
--Vending machines are everywhere. The same machine could sell beer, soft drinks, water and hot coffee. Some sell clothes. If you buy something to eat or drink from a vending machine is it okay to consume it near the machine or while sitting down. Never walk and eat or drink anything.
--Never touch the doors of a taxi. The driver will open and close the doors via a button he controls.
--learn the proper queing technique for getting on trains and buses. Never cut the queue.
--carry a handkerchief or small towel with you as many public restrooms don't have disposable towels or dryers.
--I'll let you discover the Japanese toilets. It's an experience.
--Japan is still very much a cash society. Not all Japanese ATM's accept foreign cards. However, the ones at convenience stores usually do.
--don't expect to find trash cans. They are hard to find. Most Japanese will carry their trash until they find one. Usually at a convenience store or a train station.
--learn some basic words in Japanese. English is not as widely spoken as you would think.
--there are two Godzilla statues in Tokyo. See if you can find them.
Japan is one of my favorite countries. You'll find the people to be clean, courteous and following the rules.