(Miiratori ga miira ni naru; “The mummy-hunter becomes a mummy”)
A person, sent to get someone and bring them back, themselves ends up staying away. A person who goes to convince someone of something ends up being convinced that the other side is correct. An ironic reversal. “Going for wool and coming home shorn.”
We begin with the second word, 取り. This is the verb 取る (toru), “to take,” in stem form and acting as a noun. It’s modified by compounding it with the noun ミイラ (miira), “mummy,” to make “mummy-hunter.” (Although see below for an alternate reading.) The whole is marked as the subject of the sentence by the particle が (ga). The latter half of the sentence comprises the verb なる (naru), “to become,” with the particle に (ni) indicating that the repeated noun ミイラ is undergoing the transition.
The Japanese word ミイラ comes to us, through Portuguese, from “myrrh” (Hebrew מור (mor); Arabicمر (mur)), for its use in embalming practices. It may also be written with the ateji 木乃伊, although katakana are far more commonly used in contemporary Japanese.
The most-supported explanation for ミイラ取り is of people who disinter old, mummified remains to be ground into powder for their supposed medicinal effect! They end up mummified themselves, though, becoming exactly that which they had sought to retrieve and destroy.
However, one of my sources claims that ミイラ取り isn’t a mummy-hunter, but rather a person sent to retrieve myrrh for someone else’s mummification process who ends up dying in the desert and becoming a mummy through natural action of the sun and dry air. I don’t buy this explanation, though. For starters, it has the feel of a folk etymology invented by people who think of dynastic Egypt as a bunch of idiots out wandering around in the sand rather than a sophisticated commercial empire built around a flood plain. Second, this reading would require that ミイラ carry two different meanings within the same sentence: first “myrrh,” then “mummy.”
Note that there is a (now-outlawed) Buddhist tradition of monks realizing that their time has come and arranging to die while meditating in such a way that their bodies will naturally mummify; the resulting corpses may be retrieved, decorated, and put on display to demonstrate the power of Buddhism in warding off corruption and decay. These are generally not called ミイラ, but rather 即身仏 (sokushinbutsu) – “body-as-is Buddhas.”
(“Honya-san de tachiyomi shiteru musuko wo yobi ni ittara, omoshirosou na ansorojii ga me ni tomatte, ware ni kaettara sanjuppun mo tatteta. Miiratori ga miira ni natta na, ha ha ha.”)
[“When I went to get my son, who was in the bookstore reading, an interesting-looking anthology caught my eye, and when I came to my senses over half an hour had passed. I’d gone out for wool and come home shorn.”]