In A Love to Kill, Bi/Rain/Jeong Ji-Hoon plays a tough guy as the role of a K-1 Fighter, Kang Bok-gu. Bok-gu is a character who is dynamic in nature and grew up in a foster home. He falls in love with a woman whom he should not love. It was because of the woman, his emotionally-wounded brother fell off from the rooftop and became a human vegetable. So, his love is forbidden and inevitably tragic.The woman is Cha Eun-seok (Shin Mina) who is a TV talent and movie actor. It was not that she jilted his brother on purpose, but upon a basis of misunderstanding, his hatred toward Cha Eun-soek grows more and more burning.By becoming Cha Eun-seok’s private bodyguard, Bok-gu keeps concretely practicing his revenge upon her. He only desires ‘to bring his brother’s woman to her knees.’ He is gradually taking Cha Eun-seok to destruction, while he feels his love toward her growing deeper and deeper in his heart.Bok-gu is a cold guy character without any special concern for woman. Martial art of hand-to-hand fighting was just kind of his escape he choose from the shock of a spinster’s death whom he loved from a distance.