We had a good stay with K&K, the apartment is small but clean, and was just enough space for myself and two siblings. We had to leave our luggage spread out due to limited space but we didn't mind.
The apartment was easy to find using the guide Kazumi sent before arrival. We were able to leave our luggage prior to check in too which was great.
Kazumi regularly checked in with us for the duration of our stay and had many tips and recommendations on places to see and food to try, which I appreciated.
The location is in a really quiet neighborhood, but only a short walk away from the station. It can be a bit noisy at night hearing the train on the rails and various traffic/sirens, but if you keep the windows closed it won't be loud enough to keep you up unless you are very sensitive.
The washer dryer was a great amenity, as well as the portable wifi device. We made great use out of both!
The only negatives were that the towels provided smelled of mildew so we had to wash them before using them, and the toilet started to become blocked after a few days. I had to buy a plunger, but Kazumi refunded me after I provided the receipt.
All in all it was a pleasant stay.