Responses
From just slightly skimming the other stories, it looks like shin isn’t really the main character but more like the narrator meeting the couples and discovering/seeing their story. The other stories are mainly about other couples. So this looks like this is shin’s actual story which is why other commenters have noted that they finally get to read his story. I could be wrong though since I didn’t fully read the other two.
Wait, so Shin is a main character in all three stories? I was going to ask if it would be okay to skip the first two, but I guess not. This is the only one that sounds interesting, though. I love a good master x servant storyline.