trusted subordinate; right-hand man; henchman
Refers to a subordinate who is deeply trusted and relied upon, often in political, business, or organizational contexts. Can carry a slightly conspiratorial or loyalist nuance depending on context.
The president called only his most trusted subordinates to the meeting.
彼は大統領の腹心の部下として知られている。
He is known as the president's right-hand man.
側近 refers to a close aide or attendant, often in political or royal contexts, and does not necessarily imply a subordinate relationship. 腹心の部下 specifically emphasizes a trusted subordinate within an organization.
右腕 means 'right-hand man' and focuses on being the most capable assistant, while 腹心の部下 emphasizes deep trust and loyalty, sometimes with a hint of secrecy.
腹心 (ふくしん) literally means 'belly and heart', metaphorically indicating one's innermost thoughts or deep trust. 部下 (ぶか) means 'subordinate'. The phrase combines these to mean a subordinate in whom one confides completely.