一いち人にん前まえになる

expression, godan verb (-ru)

come of age; become an adult; become fully qualified; stand on one's own

Used when a person reaches a level of maturity, skill, or independence where they are recognized as a full-fledged member of society or a profession. Often implies being able to handle responsibilities on one's own.

• 彼かれは修しゅ行ぎょうを終おえて、やっと一いち人にん前まえになった。

  After finishing his apprenticeship, he finally became fully qualified.

• 一いち人にん前まえになるまでには、まだ時じ間かんがかかりそうだ。

  It looks like it will still take time before I can stand on my own.