…but hard to shake once taken on
(Ko wa sangai no kubikase;
“A child is a binding for all time”)
A connection with a child is a strong bond that affects you for your entire life. Even after the logistical burden of child-rearing has ended, the emotional connections between parents and children means that the parents are more limited in life than if they had remained childless. This can be positive, when one is moved to act in certain ways out of love… or negative, when the bond causes distress or hardship that otherwise would have been avoided.
We begin with the particle は (wa) marking the noun 子 (ko), “child,” as the topic of discussion. The comment on this topic begins with number-noun 三界 (sangai), a Buddhist term referring to the “three realms” of past, present, and future existence. The associative particle の (no) attaches this to, and allows it to modify, the compound noun 首枷 (kubikase), “pillory.” (Literally “neck-fetters.”)
A traditional 首枷 is a flat wooden board with a hole for the neck (and often separate holes for the hands) used to restrain prisoners, often with additional restraints to make sure the person bound by one can’t just use their hands to take it off again. Be very careful with image searches, though; the term apparently can also be applied to modern bondage gear, especially collars with attached handcuffs.
Bear in mind that the 界 in 三界 can only be pronounced gai; reading it as kai is considered an error.
Variant phrases include rendering 首枷 as 首っ枷 (kubikkase) – although why is not clear – or expanding 子 to 親子 (oyako), “parent and child.” There are a number of synonymous phrases, including a delightful one that asserts that 子が無くて泣くは芋掘りばかり (ko ga nakute naku ha imohori bakari), “only potato-diggers cry for lack of children.” On the other hand, there are a number of antonyms asserting in various ways that there is no treasure greater than a child.
This is the こ (ko) entry of the Edo iroha karuta set. It is attributed to a 1700 ukiyozoushi text titled 『御前義経記』 (Gozen gikeiki).
(“Omoshiroi ne. Tomodachi no naka ni wa, ko wa sangai no kubikase dakara isshou umu tsumori wa nai to itteru hito mo ireba, seikatsu wa futarigurashi yori mo kazoku ga ooi hou ga nigiyaka de tanoshisou dakara takusan umitai to itteru hito mo iru nda.”)
[“Oh, that’s funny. I have some friends who say that children are a lifelong burden so they don’t intend to ever have any, and other friends who say that things are more lively and fun when you do them as a big family than as just a couple, so they want to have a lot.”]