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In addition, the first 4 volumes (translated!) are available to purchase off Amazon, and probably elsewhere:
I love this manga to death! Guys, remember to pre-order on Amazon! Vol 1 ships in May at which point Maigo will stop scanlation.
Not book, but The Ancient Magus' Bride deals with this trope extensively. It's recently been licensed by Seven Seas, you can pre-order it on Amazon. Or if that's unavailable in your area there are fan translations you can read at Batoto.
Highly recommend it.