Fate/true reality (Fate Series for "Idiots and Tests and Summoned Beings")

[Fate series style] In his return to Fumizuki High School, a year after graduation, the moment Akihisa Yoshii shouts the word "Summon" within an ESB field and the being called was not his avatar, but a human resembling a certain French saint, telling him that he is her "Master", things are no longer the same as before as future events are about to set on stage within the city...