I'm a replica—a copy who must fill in for their original whenever they don't want to do something. But now I've lost my one role. As winter approaches, Sunao begins to scare me. I can't tell what she's thinking at all. While she's away on a school trip, Aki and I visit Fujinomiya, Ryou's hometown. As I enjoy my first big trip, I finally begin to unravel the mysteries of the strange beings called replicas. But am I ready to face the truth of what I am, and of Sunao's secret?
Another really good entry into the series. This one dives a lot more into explaining what exactly replicas are and ends with a cliffhanger that has me looking forward to the next volume. Along the way, there are little bits of school life, friendship, and romance sprinkled in. I like that Sunao (the original) also receives some character development. Through the first book especially, she seemed especially mean to Nao (the replica) but this volume humanized her a lot and made me sympathize with her.