There are also a lot of ryokan in Tokyo but most of them do not equipped with onsen and meals.
So, it is hard to experience all the essences of ryokan (Japanese atmosphere, onsen, washoku) there.
Thus, I recommend you to stay at least one night at onsen ryokan that is close to Tokyo.
I have listed up some recommended onsen resorts, where you can enjoy ryokan close to Tokyo.
In Tokyo, there are a variety of accommodations from ultra-luxury hotels to capsule hotels.
The total number of rooms of accommodations is almost 150,000 rooms, combining hotels and ryokan.
In addition, construction and opening of new accommodations are coming up towards the Tokyo Olympics.