この古い屋敷の家主は今は海外に住んでいる。
The owner of this old mansion now lives abroad.
空き家の家主が分からず、取り壊しが進まない。
The owner of the vacant house can't be identified, so it can't be demolished.
留守中に家主の知らないうちに誰かが入り込んでいた。
While he was away, someone had got into the house without the owner knowing.