Katsuaki might be a bit hard to contact at the beginning but it's because he's a bit busy with his job, if you're patient and ready to speak in japanese with him (he's still learning english) you'll quickly learn that he has a golden heart and is especially enjoyable to hang out with.
Though that's something you may have a hard time to see if you're only staying a few days/couple of weeks
Otherwise the appartment was well located between Nippori/Nishi Nippori, big enough with all the equipment you might need for living, I strongly recommend this place if you're staying there for more than a couple of weeks !