We ( 3 adults) loved staying at Ben’s house in Yotsuya area.
The location is very convenient for quick access to metro and JR stations, and you really feel part of the locality - with convenience stores and restaurants all within reasonable walking distance. During our walks to metro, we mostly saw Japanese people who were our neighbours :)
The house is, by Tokyo/Japan standards very big indeed and quite modern. All bedrooms are good sized and the apartment is well equipped and appointed, especially the quality of the bathrooms and kitchen.
Ben was very responsive and provided helpful advice on all things, from restaurants to recycling, transport options to toilet instructions (yes, there are many different functions on a Japanese toilet)!
Definitely recommend staying at Ben's place.