What metaphors are used in When We Were Orphans by Kazuo Ishiguro?

The magnifying glass becomes a symbol and metaphor for Christopher's search for identity and focus. This was originally given to him as a joke gift on his birthday by his school friends. They were chiding him for his abnormal interest in detective work. However, he became immediately engrossed with it, alarming his friends. Not wishing to seem strange, he tries to play it off as a joke, but does not succeed. It becomes one of his most valued tools, even after he becomes a successful detective. He even takes it to Shanghai, where he takes it out to examine the amputated limb of a dead woman.