Whew. I found the garage key.
The garage key was in a desk drawer. Without a car, we never needed the key and it was put away for safekeeping. Of course, it was also half forgotten. Vague memories of "drawer" dredged up the right location after a few tries.
This morning, I return to the old house one last time to hand back all the keys and participate in a house inspection. I'm a bit nervous about this. Can I explain (in Japanese) that the living room air conditioner never worked but we didn't bother to complain? That the fancy toilet seat's bidet function was broken when we moved in? How do I ask them to please dispose of the three things we left behind (a broken monitor, a mildewed suitcase and an old tatami carpet)? Time to do some quick vocabulary acquisition!