During your one day in Tokyo, it's best to buy a Suica card that can be used in all forms of transport, such as trains and buses. It costs around 2000 yen and makes it easy to travel around the city without the need for buying multiple tickets. Travel time varies and depends on the destination and distance covered. However, Tokyo's train system is efficient and straightforward to navigate.
If you have more time, you can visit Tokyo Disneyland or Tokyo Tower to get a bird's eye view of the city. Alternatively, for a shorter trip, consider removing Tsukiji Outer Market from the itinerary. It depends on your preferences and the available time you have in the city.