The new English word for the little boy is Master
For the vast majority of Chinese friends, master is either understood as a "master's degree" or as a "master" in an industry.
But there are plenty of places in New Zealand that automatically add a tribute to little boys, especially those under the age of 12, Master.
For example, if the guardian takes the little boy to the bank to open a bank children's savings account (which is allowed in New Zealand), the child's title is preceded by a Master, plus the child's name. For example, when you buy a plane ticket, the title of the little boy on the ticket is Master.
The title, which does not reach "adulthood" until the age of 18, is replaced by the title of Mr. (Mister).
We sometimes see little boys in formal dresses in funny (or light-hearted) movies and TV shows, and it's actually naughty for adults to call them "Mister." Orthodox English, if you really need to respect these children, call him Master.
The little girl is not so elegant, married not married, from a few months to a teenager, are called Miss.