In a world where cards are everything, beasts, technology, magic, and the undead—from glorious archangels and god-slaying laser cannons to the colossal North冥鲲 and even the invisible atoms and molecules—all exist as cards. Those who manipulate cards for battle, life, and learning are called Card Masters! Gu Yu, a Card Master, possesses the ability to enter the inner world of cards… While others struggle to summon cards and cultivate relationships, Gu Yu can traverse worlds and communicate with cards heart-to-heart. After each exchange, Gu Yu's cards evolve. [Injured Snow Clan Girl]—[Ice and Snow Sword Attendant]—[Snow-Praying Sword Princess]… Eventually, Gu Yu discovers that he seems to have evolved something incredible—an Empress? Thus, Gu Yu begins his lifelong card…