noun
colonel (JASDF, JGSDF); captain (JMSDF)
Military rank used in the Japan Self-Defense Forces. Equivalent to colonel in the Air and Ground Self-Defense Forces, and captain in the Maritime Self-Defense Force.
彼は陸上自衛隊の一佐に昇進した。
He was promoted to colonel in the JGSDF.
一佐は海上自衛隊では艦長を務めることが多い。
Captains in the JMSDF often serve as ship commanders.
大佐 is the equivalent rank in the former Imperial Japanese military, while 一佐 is used exclusively in the modern Self-Defense Forces.
The rank name 一佐 is a modern Self-Defense Force term, combining 一 (one) and 佐 (assistant/field officer), following the SDF's unique rank naming system.