Junpaku no Wedding

It is McKenzie who consoles Natalie at Age 17 when the devastating news of her boyfriend's death strikes her. Seemingly indifferent to her until then, her older neighbor makes her lose herself with a strong embrace and a hot stirring kiss! That one kiss leaves her in a shock as if her entired body has been seared with his seal. Then he says, "Don't forget. I am going to show you what comes next."

(Source: Jmanga)