Shinichi Ueda points to a two-story house standing on 7-meter-tall concrete blocks, flanked by other elevated dwellings. Built on a slope, the wooden structure — part of a 1,000-unit-plus residential area developed in the late 1970s in the suburban city of Tokorozawa, Saitama Prefecture — has been vacant for three years.

Cracks run across its yellowish-brown walls. A plastic bag full of trash sits abandoned in the small weed-choked garden. The windows and screen doors on the first floor have come off their frames, letting in the wind and rain. Inside, the squeaky, uneven floor looks ready to cave in.

Ueda, secretary-general of the Tokorozawa-based nonprofit group Akiya Akichi Kanri Senta (Vacant Home and Land Management Center), says that since September his group has been entrusted by the owner, who lives in Tokyo, to check the property and report back to him. A sign tells people to direct any complaints or concerns to the NPO — to help the owner deal with the neighbors.