Chiyo Sakura is a cheerful high school girl who has fallen head over heels for the oblivious Umetarou Nozaki. Much to Chiyo's confusion, when she confesses to her beloved Nozaki, he hands her an unfamiliar autograph. As it turns out, the stoic teenage boy is actually a respected shoujo manga artist, publishing under the pen name Sakiko Yumeno! A series of misunderstandings leads to Chiyo becoming one of Nozaki's manga assistants. Throughout the hilarious events that ensue, she befriends many of her quirky schoolmates, including her seemingly shameless fellow assistant, Mikoto Mikoshiba, and the "Prince of the School," Yuu Kashima. Gekkan Shoujo Nozaki-kun follows Chiyo as she strives to help Nozaki with his manga and hopes that he will eventually notice her feelings.

The Abyss—a gaping chasm stretching down into the depths of the earth, filled with mysterious creatures and relics from a time long past. How did it come to be? What lies at the bottom? Countless brave individuals, known as Divers, have sought to solve these mysteries of the Abyss, fearlessly descending into its darkest realms. The best and bravest of the Divers, the White Whistles, are hailed as legends by those who remain on the surface. Riko, daughter of the missing White Whistle Lyza the Annihilator, aspires to become like her mother and explore the furthest reaches of the Abyss. However, just a novice Red Whistle herself, she is only permitted to roam its most upper layer. Even so, Riko has a chance encounter with a mysterious robot with the appearance of an ordinary young boy. She comes to name him Reg, and he has no recollection of the events preceding his discovery. Certain that the technology to create Reg must come from deep within the Abyss, the two decide to venture forth into the chasm to recover his memories and see the bottom of the great pit with their own eyes. However, they know not of the harsh reality that is the true existence of the Abyss.

The movie is a compilation of episodes 1-8 of the 2017 television series with new scenes added for the introduction. It covers the period from when Riko descends into the Abyss with her robot companion Reg, reaching the second layer where they meet the White Whistle Ozen who reveals information about Riko's mother. (Source: Wikipedia)

The movie is a compilation of episodes 9-13 of the 2017 television series. Riko and Reg descend to the third layer where Riko has her first experience of the Curse. They descend to the fourth layer where Riko's arm is injured by an Orbed Piercer and Reg tries to save her. Nanachi comes to their aid and saves Riko's poisoned arm. In return Nanachi asks Reg to kill her immortal companion Mitty. Nanachi then joins Riko and Reg in their quest to reach the bottom of the Abyss. (Source: Wikipedia)