One's youth; the period of being a young person, often referring to adolescence through early adulthood and associated experiences.
彼は青年時代に海外を旅して、多くのことを学んだ。
He traveled abroad in his youth and learned many things.
青年時代の友人と久しぶりに再会して話に花が咲いた。
I reunited with friends from my youth after a long time and we had a great conversation.
その小説は主人公の青年時代を中心に描いている。
The novel focuses on the protagonist's youth.