I love this house: the tatami room, the shower room, the location... Everything is so authentic and if you love the Japanese culture and Japanses way of life, I think the Mariko's apartment is perfect for you. It could be old, like Mariko describes, but I think it's not a problem.
It's easy to get from Narita and by JR Chuo-Sobu line you are in Akihabara in 15 minutes.
Besides, Mariko answers quickly your questions and she keeps a close watch on your needs.
Thanks Mariko for sharing your house.