We had a pleasant stay at Kumina's place. It was conveniently located not too far from the train station. We greatly appreciated the easy self check-in process, Wi-Fi, and the provided amenities. We were actually upgraded to another unit due to unforeseen circumstances but Kumina's communication was frequent and helpful, so we did not encounter any major problems during our stay.
The only minor issue is that I felt the unit was not really suitable for a longer stay. The kitchen had plenty of cooking supplies, but some looked a bit dirty/old, and it would have been nice if some basic ingredients such as cooking oil, salt, and pepper were provided. We did appreciate the bottle of water provided in the fridge. Likewise, laundry was a bit difficult to do as there was a lack of hangers and indoor space to hang clothing.
As with many studio apartments in Japan, the space can be a tight fit especially if you're tall. This isn't a fault of Kumina's but be aware that if you're taller than 5'5" you will feel cramped using the bathroom and your knees will most likely bump against the door.