My Boyfriend Is Type-B (2005)

Young-bin and Ha-mi meet by accident after a row over him ruining her cellphone. She believes he and she were destined to meet, but the problem is, he has blood-type B, making him spontaneous and emotional but unreliable. Her sister, running a dating-agency based on selection by blood-types, opposes the friendship, as she's convinced that Ha-mi, with blood-type A, making her soft, introvert and shy, will only end up as another victim of his whims and arrogance. Romantic comedy by Seok-won Choi.