This movie is a retelling/summary of Selector Infected and Spread, with extra scenes interspersed such as the characters in childhood. Despite mostly being previously used scenes, they were cut and altered to make a high intensity and fast paced story, highlighting the moments of slow silence and reflection. Some changes were made such as the true origin of Tama's name, the significance of Sachi and Rumi, and the relationship between your name and being alone.

(Source: Asenshi)