16-year-old super-studier Nagi Umino, second-year student at the Megurogawa 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!
The fated entrance exam day is here! Backed by Nagi’s full support, Sachi steps forward to take on the biggest challenge of her life. Will she pass and get an answer to her confession to Nagi? And the arrival of Valentine’s Day brings another difficult decision for Nagi…