We had a great time in Tokyo and at Sayaka's place. It is quit central but quiet. Metro station is just a short walk away and even Shinjuku with all the craziness ist just a 15 minute walk away. Closest 7-Eleven is just 1 minute away, if you leave the building on the left hand side. Found it on the last day. :) The days before we went to the ones on the main street in direction of Shinjuku Gyoenmae station.
Communication with Sayaka was perfect, she always replied very fast.
We can definately recommened her place.