employee transferred without family
Refers to a worker who has been transferred to a different location and lives alone, leaving their family behind. Common in Japanese corporate culture.
He is living alone in Osaka as an employee transferred without his family.
単身赴任 is the act or state of being transferred alone, while 単身赴任者 refers to the person who is in that situation.
Compound of 単身 (alone, by oneself), 赴任 (proceeding to a new post), and 者 (person).