ward assembly member; ward councillor
Refers to an elected member of a ward assembly, especially in municipal or Tokyo special-ward contexts. Although the older English gloss says 'assemblyman', the Japanese term is gender-neutral.
I consulted a local ward assembly member about the nursery school issue.
She is active as a ward councillor in Setagaya Ward.
He was elected as a ward assembly member in last month's election.
She has served as a ward assembly member for over ten years.
I heard my friend is going to run for ward assembly member next year.
区議 refers to an individual ward assembly member, while 区議会 refers to the ward assembly itself as an institution.
Used for people in formal or counting-by-seating contexts; this is the most natural choice from the given inventory.
A Sino-Japanese administrative term combining 区, 'ward', with 議 as used in legislative terms; it is understood as a shortened form of 区議会議員, 'ward assembly member'.