In the large bedroom, the beds were a little smaller than expected. Instead of 3 double beds, it was more like 2 double and 1 single. Space was tight 9 people with all the luggage but we managed to make it work. Not sure if any more than 9 would have worked.
The place is located on the 3rd floor without access to an elevator so it might not be super accessible for everyone.
Location-wise, it does require a bit of a commute since it is located further in a residential area. The closest subway is about a 8-10 minute walk and about 20 minutes on the subway to get into central Tokyo where the larger attractions are located.