This is actually the second manga based on Da Capo II in active serialization. The other manga, running in Kadokawa’s Comptiq magazine, is considered to be the “canon” adaptation of the story (i.e. it’s based directly on the game). As the title “Imaginary Future” suggests, this manga proposes an alternate deviation from the game’s premise, where fan-favourite Shirakawa Nanaka (speculated to be a descendant of the famous Shirakawa Kotori) is the story’s main heroine.