Based on the first Tengai Makyou game, that initially came out in 1989 as one of the first titles for NEC's PC Engine CD-ROM.

The young man Qin Yang was very talented and possessed the enviable cultivation artifact Star Gate. However, this luck was taken away overnight. When he was about to die, Qin Yang opened the dust-covered treasure God Bead in his body. Since then, he has restored the memory of his previous nine lives and gained a new life. At the same time, the family fell into an unprecedented crisis. Faced with many tests, Qin Yang took charge of his own affairs and relied on the experience accumulated in his nine previous lives to break through the difficulties again and again. Unexpectedly, the conspirators are still pressing forward step by step. In order to protect the people he cherishes, Qin Yang chooses to fight to the end. (Source: Bilibili, Google translated)

A music video for One Ok Rock's song I Was King from the album Ambitions.

Marina, the most beautiful mermaid in the royal Merman family, is curious about the human world. One day, she sees a handsome prince on a boat. Suddenly, a storm comes up, throwing him into the sea. Marina saves her handsome prince and guides him to the shore. Marina falls deeply in love and desperately wants to become a human. Despite the hazards, she is willing to risk it all for love. (Source: ANN)