The older child in a family (an older sibling among brothers/sisters).
上の子は今年、小学校に入学した。
Our older child started elementary school this year.
上の子と下の子では性格が違うことが多い。
The older and younger child often have different personalities.
両親は上の子に家の手伝いを頼むことが多い。
Parents often ask the older child to help around the house.