field officer
Collective term for mid-ranking commissioned officers in the Japanese Self-Defense Forces and former Imperial military, corresponding to major, lieutenant colonel, and colonel (or equivalent naval ranks).
Once you reach the rank of field officer or higher, the responsibility becomes significantly heavier.
aide; assistant (official)
chief of staff
Compound of 佐 (sa, 'assistant' or 'help') and 官 (kan, 'official' or 'government post'). The term was adopted in the modern military rank system to designate field-grade officers.