Four years after the events of SHIROBAKO the series, Musashino Animation has gone through unprecedented changes and things are looking bleak for the studio. One day, Aoi Miyamori is offered a role managing a new theatrical animation project. With only a few months left before the deadline, can MusAni complete the project in its current state? It’s up to Aoi to work alongside both familiar faces and new to finish the project in time!
Maquia is a member of a special race called the Iorph who can live for hundreds of years. However, Maquia has always felt lonely despite being surrounded by her people, as she was orphaned from a young age. She daydreams about the outside world, but dares not travel from her home due to the warnings of the clan's chief. One day the kingdom of Mezarte invades her homeland. They already have what is left of the giant dragons, the Renato, under their control, and now their king wishes to add the immortality to his bloodline. They ravage the Iorph homeland and kill most of its inhabitants. Caught in the midst of the attack, Maquia is carried off by one of the Renato. It soon dies, and she is left deserted in a forest, now truly alone save for the cries of a single baby off in the distance. Maquia finds the baby in a destroyed village and decides to raise him as her own, naming him Ariel. Although she knows nothing of the human world, how to raise a child that ages much faster than her.
While sorting through a mess of books in the staff room, Ohana happens upon one of Denroku's log books from long ago. Within it, it recounts a story of Ohana's mom when she was the same age as her.
Shortly before the start of a new semester, Misaki Fujioka visits her twin sister Mei Misaki in Yomiyama City. The girls make full use of the last days of summer, roaming around a heat-weary town and visiting various places including a shopping center and shooting stall. When they prowl around her basement, Mei expresses uneasiness about her new class, which is said to be cursed.
Craving more entertainment, the twins decide to pay a visit to the local amusement park. But the leisure of a sleepy summer day could soon turn woeful as Mei sees the color of death on her sister—an unmistakable omen that a tragedy is bound to strike.
