We spent four nights at Hiro's place with our 3 year old daughter. Hiro's parents helped us with checkin and were the most warmhearted and thoughtful hosts ever. They did go the extra mile and more to make us feel comfortable but without being nosey. The apartment is a cosy and quiet little place hidden from the bustle of the town but not too far from it, on the ground floor of a small two storey house. The walk to Shinagawa station is about 10 minutes (15 with a toddler in tow) and pleasant. Shinagawa is on the yamanote line therefore well connected and you can catch the shinkansen from there too. With Hiro's instructions we found the place very easily. The apartment was spotlessly clean and tidy, very functional as well, exactly as described. For those travelling with a small child: there are kids books and some toys in the apartment too which is handy on rainy evenings.
Many thanks to Hiro and his parents -- very much recommended!