The information to get the key to open the door was very misleading. I tried to ask to clarify (even asked my Japanese friends to call to ask to avoid miscommunication) but the response was "please read instructions we hope you find it soon"! C'mon, maybe it was either your information was not clear, or me misunderstood the instruction but when I asked, a better clarification (with a photo) was what I expected. We had to wait like 1 hour or more to find the key, the neighbor was stepping out to offer help but she could not understand what you meant also. She had to let us in her apartment to stay a while because it was damn cold.
In the end, after too many hassles (including you showing me how to open the mailbox for nothing, the mailbox had nothing to do with the key!), we got the key after eliminating all impossibilities of where the key could be. Afternoon plan was ruined, I got sick that night and my parents suffered 1 hour of Tokyo cold air.
Apart from this bad check-in, everything else was quite nice. The place was clean and it had everything you might want for a cozy stay. I do not recommend for a group of 3 though because it was not very spacious, but it is perfect for 2 persons. The location is ok, right next to subway and Lawson. Very convenient to get to Shibuya and Mount Takao. Value for money.