Me and my friend Erin stayed at Kimiyo San's house for about two weeks. First we stayed one whole week, then we went to Hiroshima/Kyoto for three days, then returned for four more nights.
The location of the house is very convenient! As someone who has stayed at many AirBnB in Japan, you're not going to get a better price for the location. The station is a 20 minute walk from the house (a nice one, with great views. Cherry blossoms when we were there) and is 20 minutes direct to Shinjuku station from there. The neighborhood is quaint and quiet. I felt safe there. The best part about the location is that there is an Aeon (big supermarket) at the local subway station. We were able to buy snacks, fruits and stuff everyday before we left. On the way home we would pick up the discounted bento to eat.
The house is modern Japanese style. Probably the most clean house I've stayed in in my entire life. Kimiyo-San made us breakfast every morning. My friend Erin, who is Vegan was even able to. I gave Kimiyo a list of things that she couldn't eat, and she tried very hard to make things for my friend. All of her breakfasts were so yummy!
She also has a small dog, Toki! They are so adorable, small, and mostly quiet. If you like animals, you will love Toki.

Finally, in regards to communication. Kimiyo San and her husband do NOT speak English. I speak a little Japanese, enough to get around, order food, and make small conversations. If you don't speak any Japanese at all you may have a hard time.
I can't wait to go back to Japan! Would definitely stay with Kimiyo again.