I don't know where to start as there is so much to say about it!
Yuki is a great host, with a wonderful sense of hospitality and always available to answer our (many) questions.
The flat is nice and big (and sparkling clean!), very comfortable, and located in a very quiet area, right in between the crowded Asakusa and the beautiful Ueno (both are in a distance of 10/15mn walking).
Downstairs is Kumiko's coffee shop, the perfect place to start the day with nice coffee and great muffins, and Kumiko is just so kind :-)
It's a no brainer, just go to Yuki's place!