'You look like someone I know.' Taco said this to a girl who named Cathy. She just missed the train. And he's gonna tell her about a story about 'Cathy'. His ex-girlfriends all have the same name-- 'Cathy'. After breaking up with the first Cathy, each of them is like a different version of her. Or more specifically, since they all look the same, they are just like the duplicates of Cathy No.1. They never really leave. Whenever Taco gets dumped by one Cathy, there'll be another one comes into his life. These girls all have a numeral tattoo on their neck. Except for Cathy No. 5, who never lets Taco see her neck no matter how much he attempts to. What exactly is on her neck? Why is Taco so obsess about it? And for the Cathy who is missing her train-- what does she have to do with Taco's story?