A divine dragon who once guarded Dragon Star wakes from a long sleep brought on by grave wounds from an ancient war against alien invaders. Gu Zhengfeng finds his world greatly changed, and the dragon people once honored is now spoken of as an evil one. To learn the truth and recover a treasure hidden inside Dragon King Academy, he takes human form and joins the school as a mentor. A mistake places him in the Dragon Slaying Department instead. He teaches his students with care while hunting for the treasure. When he learns that everyone who knew of the Dragon King's treasure has died, his best remaining lead is Vice Dean Ye Jiangxue, whom he helps on several occasions as he draws closer. A mysterious force also has him in its sights, and after slipping past repeated assassination attempts, he senses the old threat returning. He must find the treasure to regain his strength and shape his students into a new Dragon Legion. The ONA mixes action, fantasy and science fiction.