DL: Zettai Kareshi Mode.. ON!!! [updated 200903.31]

Riiko Izawa has never had a boyfriend and she has been rejected by every boy she has ever had a crush on. When she returns a lost cell phone to an oddly dressed salesman, she mentions wanting a boyfriend so to thank her, he directs her to his company's website. When she visits the site, Riiko finds it's a site to create your own lover. Thinking its a game, she customizes and accidentally orders one. The next day, her new lover arrives. Following the instruction manual, she kisses him to wake him up and configure him to be in love with only her. She names him "Night." Three days later, Gaku Namikiri, tells her that she must now pay 100,000,000 yen for Night, however, they will waive the fee if she helps them to collect data about how women think and feel to help perfect future models. Riiko must now keep Night's true nature of not being human a secret from everyone around her. She also soon finds herself in a love triangle between Night and her childhood friend Soshi, who declares his love for her out of fear he will lose her...

Summary credited to: http://en.wikipedia.org/wiki/Absolute_Boyfriend