Discounted marriage - Kassankon

...In the old Chinese marriage system, which required the consent of the main couple's grandparents and parents, engagements were usually arranged by family members and relatives regardless of the will of the parties involved, and finger-belly marriage was one extreme example of this. The phrase "split collar (衫)" is a custom in which the collar of an infant's juban (kimono) is torn off and each family keeps it as a sign of engagement, and it is called "split collar marriage" or "split kimono marriage." Child marriage was common from the Yuan dynasty onwards, but there were also cases where it was arranged before birth, like finger-belly marriage. ...

*Some of the terminology that refers to "warikon" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…主婚者たる祖父母･父母の同意を必須として成立した旧中国の婚姻制度では，当事者の意志とは関係なく，家族や親族主体で婚約が取り決められるのが通常であり，指腹婚はその極端な例の一つである。なお〈指腹割衿（きん）(衫（さん）)〉と熟語で呼ばれる〈割衿(衫)〉は，衫襟（さんきん）すなわち幼児のじゅばんのえりをお互いにさいて両家がそれぞれ所持して婚約のしるしとする風習で，〈割衿婚〉〈割衫婚〉といわれる。元代以降，一般に行われた幼婚であるが，指腹婚のごとく出生前に取り交わされる場合もあった。…

※「割衫婚」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報