Have you ever wondered if your blood type has some sort of influence on your characteristics?
If you have Rh-negative blood, you may be interested to see if you fit in with others who have the same blood type status, or if you go against the trend and break the mold!
Ha-mi, feeling that their fortuitous meeting is a sign that they might be destined for one another, decides to pal around with Young-bin and see if there's any chemistry between them.
Taken by Ha-mi's sincerity and her willingness to pick up the check, Young-bin jumps at the opportunity.
But Ha-mi's cousin, Chae-young (Shin Yi) isn't quite so enraptured with Young-bin and tries to dissuade Ha-mi from pursuing him.
The thing is, Chae-young is a professional dating consultant and a strong subscriber to blood type theory.
Lee Dong-gun portrays title character Young-bin, a handsome but obnoxious young man who begins the film by breaking off a relationship in a most impolite way: after waiting in a parked car so Young-bin won't get a ticket, the girlfriend reads him the riot act upon his return, prompting Young-bin to slip into the driver's seat, break up with her, and speed off, leaving his new ex-girlfriend stranded in the parking lot.
From the get-go, Young-bin is not exactly a class act.
As is typical in this kind of film, the two meet purely by chance: Ha-mi accidentally text messages Young-bin before literally bumping into him.According to her, any relationship between the mismatched duo would be doomed to failure because Young-bin is a type-B male, which supposedly makes him arrogant, hardheaded, and generally a jerk, whereas Ha-mi is a type-A female, one who supposedly can't help being timid and obedient.But while Chae-young predicts impending doom, the happy couple try to give love a shot, ignoring their supposed blood type incompatibility.If you have Rh-negative blood, you probably have some of these traits on the list--maybe all of them!
The basic premise of the film comes from the Japanese blood type theory of personality, which claims that a person's blood type can determine their personality traits.The heroine is type A (conservative and introverted) while her love interest is type B (passionate and irresponsible).