We did all of these areas in two days, but they are part of the same side of the city so they can be considered similar. If you start from Otemachi metro station (which is a big one, being very close to all the government buildings) you can visit the Higashi Gyoen Garden before having a glimpse of the Imperial Palace. If you don't have a lot of time in Tokyo, I would skip this, because there's no much that you can visit of the palace, besides the gardens and the huge moats.
From there you can walk through the working districts of Otemachi and Kanda (you basically follow the train tracks where the Yamanote Line also passes) and you will reach Akihabara pretty quickly. This neighborhood is a buzzing shopping hub famed for its electronics retailers, ranging from tiny stalls to vast department stores like Yodobashi Multimedia Akiba. Venues are specialized in manga, anime, and video games so enter in one of them to experience the crazy world of Japanese pop-culture and video games! What we were happy to discover nearby, was the peaceful Kanda Shrine, which has also a cute little museum attached.
Walking to Asakusa could be a bit of a stretch, but by metro it is only a couple of stops away. This is where the number one attraction in Tokyo is, the famous Sensoji Temple, so you shouldn't be surprised by the floods of tourists that pass through this area, especially on the souvenirs-stalled street that connect the temple to the Kaminarimon Gate. But around the area there are many old traditional shops and also a number of good restaurants, including the one where our friend Tamako and her brother took us to taste the delicious Sukyaki (or Japanese Hotpot), on the covered Asakusa Shin-Nakamise street.
One thing that I did with Luigi in 1999 and wanted to do again with the girls in 2019, was to take the ferry boat from Asakusa along the Sumida River, which I would also highly recommend! You start from the Tokyo Cruise Station, overlooking the famous Asahi Flame building and you enjoy a lovely boat ride (we took the old boat) down to the wonderful Hamarikyu Gardens, right after passing the old Fish Market of Tsukuji (now only partially open to the public). We loved this beautiful paradise in the middle of Tokyo, where you can also taste a delicious tea with treats in the famous Tea House. The gardens are near two other very elegant parts of the city, Shimbashi (where many luxurious hotels are) and right next to it, Ginza. This is a popular upscale shopping area of Tokyo, with numerous internationally renowned department stores and boutiques (like the beautiful Hermès building overlooking the Sony Park square, or the eleven-floor flagship store of Uniqlo) and restaurants. It is considered to be one of the most expensive, elegant, and luxurious streets in the world. If you keep walking up North you will end up in another very busy area around Tokyo Station, where also one of the biggest underground malls, Yaesu, is. The northern façade (from the Marunouchi side) of the train station, as big as it can be in a city like Tokyo, has been recently renovated, exposing the original old red brick colonial building - and the whole square in front of it is pretty neat. From here you are exactly back at the Imperial Palace where we started!