Running into your new stepsister in the bathroom is not the best way to make a good first impression, which Basara Toujou learns the hard way. When his father suddenly brings home two beautiful girls and introduces them as his new siblings, he has no choice but to accept into his family the Naruse sisters: busty redhead Mio and petite silver-haired Maria. But when these seemingly normal girls reveal themselves as demons Mio the former Demon Lord’s only daughter and Maria her trusted succubus servantBasara is forced to reveal himself as a former member of a clan of “Heroes,” sworn enemies of the demons. However, having begun to care for his new sisters, Basara instead decides to protect them with his powers and forms a master-servant contract with Mio to keep watch over her.
With the Heroes observing his every move and the constant threat of hostile demons, Basara has to do the impossible to protect his new family members. Moreover, the protector himself is hiding his own dark secret that still haunts him to this day. Godou Kusanagi, a former middle school baseball player who had to retire due to injury, is asked by his grandfather to return a stone tablet to a friend in Sardinia named Lucrezia Zora. After meeting the demonically manipulative sword-mistress Erica Blandelli, he encounters the god of war, Verethragna. After killing the god, Godou becomes a Campione, or god slayer. His duty is to fight heretical gods who start changing things to suit themselves, usually at the expense of the people in the area. One of the problems associated with being a Campione, is that his status keeps attracting attention and difficult girls. Erica, who strongly professes her love for him, usually creates awkward and misunderstood situations for him in particular. Every time he fights a god, he kisses one of the girls he has brought with him.
Phantoms: supernatural entities such as ghosts or youkai that, until recently, were thought to be superstition. However, when a virus that infects the brain spreads throughout society, people’s perception of the world changes as the mythical beings are revealed to have been living alongside humanity the entire time. This virus has also affected those of the next generation significantly, allowing them to develop special abilities that they can use to fight against dangerous phantoms.
Haruhiko Ichijou and Mai Kawakami are two of those that were granted such power as Haruhiko wields the ability to summon and seal phantoms through drawings while Mai imbues the power of the elements into martial arts. Together, along with the friendly phantom Ruru, they form Team E of Hosea Academy which is dedicated to dealing with these often mischievous beings. In a world where the real and surreal intertwine, Musaigen no Phantom World follows the adventures of a group of friends as they handle the everyday troubles caused by phantoms.
Yuuji Kazami is a transfer student who has just been admitted into Mihama Academy. He wants to live an ordinary high school life, but this dream of his may not come true any time soon as Mihama Academy is quite the opposite. Consisting of only the principal and five other students, all of whom are girls, Yuuji becomes acquainted with each of them, discovering more about their personalities as socialization is inevitable. Slowly, he begins to learn about the truth behind the small group of students occupying the academy—they each have their own share of traumatic experiences which are tucked away from the world.
Mihama Academy acts as a home for these girls, they are the “fruit” which fell from their trees and have begun to decay. It is up to Yuuji to become the catalyst to save them from themselves, but how can he save another when he cannot even save himself?