Dissertations of my Sister, Sister, Sister, and I

AU. Hikigaya, Hachiman, age seventeen, was an ordinary student enrolled into his second year of highschool. He was a person who, if asked about, people would know the name, but not the face, sort of deal; he lived an ordinarily mundane life that didn't bother him in the slightest. However that all changes when he is suddenly introduced to his three new step sisters!