The stage is the growing city, Kamihama City. "Will you fight alongside me?" The meeting between the girls spins a new tale.
Guided by a mysterious power, magical girls gather in this city. It is a place where magical girls can stay as they are. The girls draw out new power in their fight against witches.
"What's going on... in this city?" Tamaki Iroha came to this city following her disappeared sister. Iroha works with other magical girls to search for clues.
Eventually, Akemi Homura, a magical girl from Mitakihara City, came to Kamihama as well. "If I can figure out what's happening in this city, I may be able to save Kaname-san...".
When the magical girls from the two cities cross, a new hope is born.
(Source: magireco.com/story; Translation: reddit.com/u/CarVac)