new adult (in Japan, a person who reaches adulthood that year)
新成人が記念撮影をした。
The new adult took a commemorative photo.
市長が式典で新成人に祝辞を述べた。
The mayor delivered a congratulatory speech to the new adults at the ceremony.
新成人が集い、大人としての門出を祝った。
The new adults gathered and celebrated their new beginning as adults.