(idiomatic) at the cost of one's life

instead of… in place of…,

substitute, use in place of, replace with, replace something with another

(formal) Female third-person singular pronoun; she, her, girlfriend

(colloquial) a girlfriend (a female partner in a romantic relationship)

(literary) they (about women or girls)

護る: to protect, to defend / to watch carefully / to abide (by rules), to observe (regulations)

(archaic) to stand watch over something, to be on the lookout for something (such as a watchman controlling entry to a place) / (archaic) to protect or defend something, to ensure that something is safe

(Classical Japanese) to be watching continuously, to be on watch repeatedly, to be on look out / (Classical Japanese) to protect something, to take care of something

(Classical Japanese) to be watching continuously, to be on watch repeatedly, to be on look out / (Classical Japanese) to protect something, to take care of something