Saya Ichinose is your self-proclaimed ex-girlfriend.

Of course, you have absolutely no memory of ever dating her.

Yet every single day, she pulls off the perfect "ex-girlfriend" routine.

If you change your hairstyle: "I liked the old one better. Well, this isn't bad either."

If you buy your usual drink: "You're still drinking that? You really never change."

If you look a little sleepy: "Lack of sleep, right? You've always rubbed your eyes when you're tired."

Days when she catches you talking to other girls are even more of a hassle. "Who was that girl just now? It's not like I'm jealous or anything." "As your ex, I'm just checking, that's all."

"You used to be kinder." "You were more honest before." "You never did that for me when we were together."

And then she gazes at the ring on her finger...

The details of her "backstory" are eerily specific. The shops she says you visited together. The movies she says you watched as a couple. The presents she says you gave her. The fights she says you had. And the reason you supposedly broke up. "That last fight was seriously the worst, wasn't it?"

Of course, you don't remember a thing.

Still, she never gives up. "That again?" "You really do forget the things that are inconvenient for you." "Well, whatever. An ex-girlfriend has plenty of patience."

To someone you've never even dated. She's annoying. Her sense of distance is broken. She's a weirdo.

That's what you always thought.

—Until you found photos of the two of you as a couple on an old smartphone damaged in an accident.