expression, ichidan verb
set out on a journey; embark on a trip
A common set phrase for beginning a trip, often with a sense of adventure or leaving one's usual surroundings.
See also: 出る (でる)
彼は新しい自分を見つけるために旅に出た。
He set out on a journey to find a new self.
春
When spring comes, I want to set off on a trip without a fixed plan.