Translation guide
In Japanese, how you refer to your younger brother depends on the social context. When talking about your own younger brother to someone outside your family, use 弟 (otouto). When addressing him directly or talking about him within your family, use his name or a family nickname. There is no single word that works in all situations.
Talking about your own younger brother to someone outside your family, such as a colleague, teacher, or acquaintance.
The standard humble term for one's own younger brother when speaking to outsiders. It is neutral and polite.
Calling your younger brother by name or nickname when speaking to him.
In Japanese families, younger siblings are typically addressed by their first name, often with an affectionate suffix like くん (for boys) or ちゃん (for either gender, especially young children). Using 弟 to address him directly would sound unnatural.
たけしくん、ちょっと来て。
Takeshi, come here a moment.
けんちゃん、ご飯だよ。
Ken, dinner's ready.
Some families use nicknames like お兄ちゃん (onii-chan) for an older brother, but for a younger brother, a shortened name or cute nickname is more common.
たっくん、遊ぼう。
Tak-kun, let's play.
Talking about the younger brother of a person you are not close to, or in a formal setting.
The polite form used when referring to someone else's younger brother. It adds the honorific さん.
田中さんの弟さんはおいくつですか。
How old is your younger brother, Mr. Tanaka?
A very formal and respectful term, used in business or ceremonial contexts.
社長の弟様でいらっしゃいますか。
Are you the company president's younger brother?
Talking about younger brothers in general, or in a narrative context.
The same word is used in general statements, but without the possessive, it can mean 'a younger brother' or 'younger brothers' in general.
弟は姉を尊敬することが多い。
Younger brothers often look up to their older sisters.
Literary term for the youngest brother. Used in formal writing or historical contexts.
In Japanese, you never call your younger brother 弟 to his face. That would be like calling him 'my younger brother' in English. Always use his name or a nickname.
弟 (otouto) is for a younger brother, while 兄 (ani) is for an older brother. The distinction is absolute and based on birth order, not age difference. Even a twin born minutes later is 弟.
When addressing your younger brother, adding くん (kun) is typical for boys. ちゃん (chan) is more affectionate and often used for young children. Using no suffix can sound blunt or masculine.
弟は私より背が高いです。
My younger brother is taller than me.
彼女の弟さんは医者です。
Her younger brother is a doctor.
彼は末弟として甘やかされて育った。
He grew up spoiled as the youngest brother.