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!

Rose, Ryuji and Eriko are suddenly invited to the Japanese branch of the society by a researcher named Tokura. While Rosa is indistinguishable from a young girl, the society performs a variety of examinations after hearing she is a dragon, and the results are...! Unconcerned by her situation, Rose is simply happy to be with Ryuji, and enjoys eating ice cream. However, a young man in black and an underground broker come for Rose!

Rose is kidnapped! The youth known as Onyx uses the tremendous power of the black dragon to subdue her. Onyx, who refers to Rose as "princess", seeks to make her his bride! Ryuji faces his emotional scars, unleashes the powers of a slash breath short sword, an S Class Lost Precious left to him by his parents, and goes after Onyx to save Rose. However, an insurmountable wall exists between humans and dragons. Emotions clash as the battle begins! Rose is kidnapped! Onyx, the youth in black, uses the tremendous power of the black dragon to subdue her. Ryuji faces his emotional scars and decides to fight. Emotions clash as the battle begins!