Family name クスイ (クスイ 
, Kusui 
) , worldwide, is a very rare surname. The family name クスイ is characteristic of New Zealand, where it is a very rare surname, Malaysia, where it is an extremely rare surname, and the United States. Not in comparison with a country's population, it is the most numerous in Malaysia, India, and New Zealand. Much more prevalently, クスイ is the forename as well as the last name.