noun
rear admiral (JMSDF)
Specific rank in the Japan Maritime Self-Defense Force, equivalent to rear admiral (lower half) in the US Navy.
彼は海将補に昇進した。
He was promoted to rear admiral (JMSDF).
海佐 is a lower rank (captain), while 海将補 is a flag officer rank.
Compound of 海 (sea) + 将補 (general-supplementary), modeled after the naming pattern of JMSDF ranks.