For millennia, the ancient and mysterious Dragon Clan has thrived on the Central Continent. Yet the struggle between the Light and Dark Souls of the Divine Realm drags the dragons into conflict. The clan is torn apart by brutal civil strife, facing the threat of extinction. In this desperate hour, Ao Xue, the long-absent prince of the East Sea, returns with formidable power, determined to save the Dragon Clan from peril.

A thousand years ago, the divine general Fei Peng and the Demon Sovereign Chong Lou engaged in a fierce battle in the New Immortal Realm. The divine sword "Zhao Dan" fell to the mortal world, and Fei Peng was demoted to earth. A millennium later, the Lock Demon Tower of Shu Mountain trembled, and Fei Peng's reincarnation, Jing Tian, who obtained the demonic sword, embarked on an adventure alongside Tang Xuejian, Xu Changqing, and Zi Xuan to collect the Five Spirit Orbs and seal the Lock Demon Tower.

Ren Homura has just moved back to his hometown of Kaminohara, but he is not able to remember much about the time he spent there other than vague flashbacks. When he retrieves his cell phone which he had sent to a shop for repairs, he finds that a mysterious game titled "Monster Strike" has been installed on it. Unaware of its purpose or how it got there, Ren decides to open it, an action that will change his life forever as he finds himself suddenly attacked by a strange man. Now trapped on the roof of his school which strangely has been designated as a "stage," Ren is shocked to see the man summon a realistic monster from the game, one that is more than capable of inflicting damage on a human. His only chance of getting out of this situation alive is by summoning the dragon Oragon, who tells Ren that he will crush the opposing monster for him. Unfortunately, it turns out that Oragon is a tiny dragon that is completely useless!

Based on the gag manga by Fujio A Fujiko.