Kaoru's apartment is a real jem in Tokyo. It's comfortable and roomy (for Tokyo's standards!), and being at the 7th floor it's out of reach for loud noises (but all the city is surprisingly quiet. We love it).
The neighborhood is peaceful and full of interesting little shops and restaurants, with a nice temple nearby and the Waseda University buildings.
Kaoru was a great host, and even if we didn't met him in person, we chatted through Line and he was always very kind and helpful.
We absolutely recommend this place for visiting Tokyo :)