16-year-old super-studier Nagi Umino, second-year student at the Meguro River Academy high school, was switched at birth. On his way to a dinner to meet his birth parents, he accidentally meets the brash, outspoken, Erika Amano, who is determined to make Nagi her fake boyfriend as she never wants to actually marry. But once Nagi makes it to dinner, he finds his parents have decided to resolve the hospital switch by conveniently having him marry the daughter his birth parents raised...who turns out to be none other than Erika herself! After Ai-chan's identity and love declaration become public, Nagi finds himself as an overnight celebrity. Meanwhile, Hiro, who's been a fan of Ai Mochizuki for a long time, is feeling very conflicted, and sparks are about to fly when she asks Nagi to meet him after school... To make matters worse, it's not long before Nagi and Erika find themselves locked in a hotel room to avoid the media! The fiery love pentagon gets even more intense!