The film is an adaptation of a story in Chinese mythology (in particular, the epic fantasy novel Fengshen Bang) about the warrior deity Nezha. After a gestation period of 3.5 years, Lady Yin, the wife of General Li Jing, gives birth to a flesh ball, which becomes a lotus flower, from which Nezha is born. Nezha is born able to walk and talk, and is taken on as a student of the immortal Taiyi Zhenren. The Dragon Kings of the Four Seas, tired of being peaceful, have become cruel and destructive, plaguing China with destructive storms and a drought. The people beg for rain, but the East Sea Dragon King Ao Guang ignores them, telling the yaksha Ye Sha to go and find children for him to eat. Ye Sha captures one of Nezha's friends as he is bathing by the ocean, and Nezha confronts him, injuring him badly. Ao Guang sends his third son, Ao Bing, next. Ao Bing is killed by Nezha, infuriating Ao Guang. A variety of confrontations ensue between Nezha and Ao Guang. Ao Guang and the other Dragon Kings wreak havoc on the people, causing storms, floods and all manners of natural disasters. Seeing this, Nezha takes his father's sword, tells his parents that he is returning their flesh and bones to them, and calls out for his master before committing suicide by slitting his throat. He is reborn with the help of his master, again from a lotus blossom, and is given new weapons and abilities. After breaking into Ao Guang's underwater palace, he confronts Ao Guang and the other Dragon Kings again, and is finally triumphant.

Kozuki Mai is an elementary student who wants to be a magician and perform in her family's "Magicarat" magical act; however, she is too young, and her magic skills are not very good. Then one day, she encounters a ball of light that was put into a stuffed doll of flying squirrel, bringing it to life and somehow giving her the power to turn in to the 18-year-old magician "Magical Emi." As Emi, Mai was able to join the magic act. But she must keep her identity a secret from her family and from her crush.

An animated pilot film for Ninja Bugei-chou released to the public over three decades later on Ninpuu Kamui Gaiden DVD volume 7. The pilot film was created in 1969 as director Nagisa Ooshima was wanting to make a TV animation to build off his controversial film from 1967. The pilot was rejected by Shirato himself (the original comic creator the film was based on) and the plan was changed to animate Ninpuu Kamui Gaiden instead, a side story to the Kamui Den manga also created by Shirato. Though with this change, Ooshima did not partake in Ninpuu Kamui Gaiden's production.

Based on the novel trilogy of the same name by MAYUMURA Taku (眉村 卓), Time Stranger is the story of a bunch of teenagers getting transported back in time through Japan's history, and getting mixed up with samurai shenanigans.