To really grasp Tokyo, its usually recommended to plan 2 weeks stay. Being there for 4 days I would agree that 2 weeks can be very reasonable. Although, to get the idea, observe main areas and taste the most known foods, if planned well, shorter visit will work as well.

Tokyo has efficient public transportation system which will help you to get around. It will still take time, but keep in mind, you are getting around in one of the biggest city in the world.

I would recommend purchasing internet plan (pocket wi-fi or e-sim) since city is huge and navigating there might be a challenge. Having internet and Google maps on hand has been the best help to move around smoothly. Tokyo also has huge train/subway, which is very likely to be used and those stations have many lines, many entrance points and many platforms and Google maps most of the time has some directions how to navigate inside the station, which also proved to be very helpful!

Main way of moving in Tokyo will be subway – there are two companies that operates subways and they use different routes and different payment systems, but it is very clear in which subway you are about enter and they all have ticket machines just before you get in the station, so it has not been confusing at all.

Taxis are more expensive option, but Japan has interesting taxi etiquette, so its fun to try at least once!

And practically the most important thing is to taste as much as possible. Eating in Tokyo and Japan overall has been not only the food but also the whole experience.