Maijima Academy is in an uproar because the current most popular orthodox idol, Kanon Nakagawa (who's actually a student there!), is coming for the first time in two months!! Keima is playing his games on the roof of the south building when he happens to run into Kanon. Kanon panics when she discovers that Keima doesn't recognize her, a national idol! Why is she so obsessed with drawing attention to herself?!

A short break from hunting down loose souls! Keima is finally free to toil away at his dating sims, but now there's a game that the "God of Conquest" cannot conquer...!? Keima begs (intimidates) Elsie into helping him conquer the buggy mess that everybody's talking about, "Crayon," the game with an ending nobody's ever seen. Elsie watches as Keima desperately tries to "save" the heroine Sora Asuka...

The next loose soul was hiding in Maijima Academy's resident rich girl and daughter of the owner of a big company, Mio Aoyama. Keima and Elsie followed Mio home and discovered that she was actually living in a run-down apartment. Now that Keima knows Mio's secret, he offers to become her new driver! He continues to take care of Mio while enduring the abusive title of "commoner." And then one day, Mio receives an invitation to a high society party...

Keima and Elsie have successfully conquered Ayumi and captured the loose soul. ──But they haven't completed their contract yet...!! Elsie transfers into Keima's class, declares that she's his little sister, and announces that she's going to live in his house as well! All for the sake of rounding up the loose souls in this city... Who holds the next loose spirit? And will Elsie be able to become Keima's little sister??

Katsuragi Keima, a high school sophomore in class 2-B of Majima Academy, is a dating sim master and known as the "God of Conquest." Elsie, a demon descended from Hell, comes to speak to Keima for entering into a deal with the devil. In order to protect his life, he must capture the "Loose Souls" which exist in people's hearts. To do this, he must make real-life girls fall in love with him! A loose soul escapes into his classmate, track-and-field athlete Takahara Ayumi's heart. Will he really get her to fall in love with him?!