He is a hanger-on at his relatives' house.
person given the cold shoulder; unwelcome guest
Describes someone who is treated coldly or ignored by a group or household, as if they are only given cold rice to eat. Overlaps with sense 1 but emphasizes the cold reception rather than dependency.
The newcomer is still treated like an unwelcome guest.
non-inheriting son (Edo period); younger son with no inheritance
Historical term from the Edo period. Refers to younger sons who could not inherit the family estate and were often dependent on the eldest brother or other relatives, hence metaphorically 'eating cold rice'. Familiar language.
In the Edo period, 冷や飯食い referred to second sons and younger.