(figuratively) driving force

(mahjong) a winning hand using special rules; worth 48,000 points if the winning player is on the East (dealer) side or 32,000 points otherwise

auditor (one who audits bookkeeping accounts)

(mahjong) a win worth four times of a 満貫 (mangan): 48,000 points if the winning player is on the East (dealer) side or 32,000 points otherwise

(Japanese fiction, pornography) the one who fucks other characters

(military) reserve service

one who sets fire / (by extension) one responsible for something's popularity, etc.

one person / singleness, singularity / one's own efforts or strengths / an unmarried person, single

one person

a person, human / an individual / mankind, people / character, personality / an average person / (law); an adult / someone (else)