Translation guide
In Japanese, the concept of a person who has come of age is most commonly expressed with the term 成人 (seijin), which refers to someone who has reached legal adulthood (currently 18 in Japan). Other expressions exist for specific contexts, such as emphasizing maturity or responsibility.
Referring to someone who has reached the age of legal majority (18 in Japan as of 2022).
The standard term for a legal adult. Used in formal and everyday contexts.
彼は今年成人になった。
He became an adult this year.
成人の日は1月の第2月曜日です。
Coming of Age Day is the second Monday of January.
A more formal or legalistic phrase meaning 'a person who has reached the age of majority'. Often used in legal documents.
成年に達した人は、親の同意なく契約できます。
A person who has reached the age of majority can enter into contracts without parental consent.
General word for 'adult'. Less precise than 成人, but very common in everyday speech. Can also imply maturity rather than just legal age.
もう大人なんだから、自分で決めなさい。
You're an adult now, so decide for yourself.
Specifically referring to someone who has recently turned 18 and is participating in Coming of Age ceremonies.
Refers to a new adult, especially those celebrating their coming of age in the current year. Commonly used around Coming of Age Day.
新成人の皆さん、おめでとうございます。
Congratulations to all the new adults.
Emphasizing emotional or social maturity rather than legal age.
Means a full-fledged adult, someone who is independent and responsible. Often used when someone acts maturely.
彼はもう一人前の大人として扱われるべきだ。
He should be treated as a full-fledged adult now.
Can also imply maturity in behavior, though primarily legal.
成人としての自覚を持ちなさい。
Have the awareness of an adult.
As of April 1, 2022, the legal age of adulthood in Japan was lowered from 20 to 18. However, certain activities like drinking and smoking still require being 20. The term 成人 reflects the legal definition.
成人 (seijin) is a formal term for a legal adult, while 大人 (otona) is a more general word for an adult that can also imply maturity. In casual conversation, 大人 is more common, but in official contexts, 成人 is preferred.