My wife, two young kids, and I had a wonderful time staying at Sunnyside Cottage.
Upon arrival, the cottage was very clean and easy to access.
It has everything you need for a short stay, even a washer and dryer, with a booklet/signs on how to use various appliances, how to check out,
and information to local restaurants, etc. (in English and Japanese).
On rainy days, our kids amused themselves with available toys and some card games. On sunnier days, the kids enjoyed laying on the hammock while I barbequed in the yard.
There is plenty of room in the yard to eat outside (the cottage comes equipped with outdoor table and chairs) if the weather is nice.
As the cottage is surrounded by forest,
there are quite a few insects so if you do eat outside, be sure to use the mosquito coil and other bug repellents available in the cottage (if you are really prone to bug bites,
best to wear long sleeve, long pants). Owner was very prompt to respond (in English) to any questions before and throughout our stay.