This is a very comfortable Japanese-style room, by which is meant a tatami room with a very compact kitchen area, Japanese bathroom and toilet. It is perhaps worth pointing out, especially to western guests, that "Japanese -style" means that everything in the tatami room is at floor level: sleep on futons on the floor, fold them away during the day and sit on cushions on the floor. If you're not comfortable sitting/sleeping on the floor, this might be an issue.
Kenji was extremely helpful and promptly sorted out a problem with the wifi that arose near the end of our stay.
Regarding things to do in the area, be aware that tickets for the Ghibli museum have to be reserved AT LEAST a month in advance. On the other hand, quite nearby is the Edo-Tokyo open-air architectural museum, in Koganei park, well worth a visit.
Kenji's house was a perfect base for our two-week family . Arigatou gozaimashita.