High school student Ryuji's older cousin Eriko returns from abroad to drag him to the scene of an underground transaction where he gets caught up in a shoot out and car chase! While they thought they had stolen a miraculous Lost Precious from the criminal brokers, they ended up with a mysterious young girl! The young girl happily latches on to Ryuji even though they have never met! Who is this little girl? Thus begins the story of the beautiful young Rose and Ryuji!

Ryuji wakes up finding Rose dressed up in his school's girl uniform saying she wants to go to school too. Ryuji agrees but makes her promise that she wont use her wings and fire. When they get to school, class is suddenly disrupted by by Bianca Alexandra Lou, a women sent by the society to evaluate Ryuji. She fires a SMAW at Ryuji and finds his physical level is 326 and his lost precious level is 120 . She seems slightly disappointed and says she will test his maximum lost precious level later. After a whole bunch of questioning, Bianca takes Ryuji outside to start the test. Ryuji needs to battle a Neogolem. After Ryuji severely hurts it and the Neogolem still doesn't shut down, Bianca realizes that there's something wrong with it and tries to automatically shut it down when it doesn't work, she climbs up the robot trying to shut it down manually. Ryuji and Rose engage and stop the Neogolem. At the same time all this happens, Eto figures out it's Ryuji's birthday the day after and tries to figure out what to get him for his birthday present.

Rose wakes up with no memories about her life with Ryuji and her friends. Not willing to take any chances, Onyx decides to leave Japan with her as soon as possible. Meanwhile, thanks to Maruga's counseling, Ryuji finally comes to terms with his feelings for Rose and together with all his friends, he sets to Haneda Airport to rescue her.