Kyoko's place was very comfortable for 8 of us, all adults. There was ample space to lay out our suitcases in the downstairs rooms. The Japanese room upstairs has room too, or you can lay them just outside the room behind the bookshelves for some privacy, and use the coat hanger in place of a wardrobe to hang clothes.
During the middle our trip we stayed away for 2 nights at an onsen, and Kyoko allowed us to keep our luggage in the house by letting us book those 2 nights at a discount. After the discount, the price of keeping the luggage there was about the same as using a storage service, but without the hassle of packing and carrying the suitcases.
Shimo-kitazawa is great, there's something for everyone - supermarkets & Muji for the domestic ones, cool boutiques and 2nd-hand stores for shoppers, izakayas for drinkers, a good range of restaurants to accommodate different tastes or those with allergies. (In our case, seafood) We found an affordable place to eat A5 wagyu yakiniku as a family - Yazawa Beef! After that we wandered around, went for late-night karaoke and just walked home. Shindaita, the nearer station, is quiet with nice houses around.
Kyoko's instructions are simple and clear, just follow them and you'll be fine.