Been first time in Japan, and i can say i enjoy staying at Sayoko apartment.
It is a really strategic place between shinagawa and tokyo. If you want to wondering around the city, i would recommend this place. It is located in osaki and the neighborhood is quite nice. But i would recommend to bring medium luggage to make your life easier here. Not to mention Sayoko is a lovely host, with amazing hospitality and respect your privacy.
I would recommend sayoko to other people :)