Even a Replica Can Fall in Love Vol.3

WHAT ARE REPLICAS, AND WHERE DO THEY COME FROM? I'm a replica--a copy who must fill in for her original whenever she's asked. But now I've lost my purpose, and Sunao, my original, is starting 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 Ryou's hometown, and I finally begin to unravel the mystery of my creation. But am I ready to face the truth of what I am and the secrets Sunao has been keeping from me?