also: だんじょしちさいにしてせきをおなじゅうせず
expression
after age 7, boys and girls should be kept apart
A Confucian-derived proverb stating that from around age seven, unrelated boys and girls should not sit together or interact freely. In modern Japan it is often cited as an old-fashioned moral precept rather than a practical rule.
「男女七歳にして席を同じゅうせず」という言葉は、今では古い考え方だと言われる。
The saying 'after age 7, boys and girls should be kept apart' is now considered an old-fashioned way of thinking.
From the Chinese classic 'Book of Rites' (Liji), later adopted in Japanese Confucian education. The exact derivation is uncertain, but the phrase has been used in Japan since at least the Edo period.