773 is a Japanese developer that has primarily developed visual novels.
773 (pronounced “nanami” in Japanese) consists of just one full-time member who goes by the handle “Hizume” and several members who contribute to development projects purely as required. Hizume oversees all development projects and personally heads up game design, script writing, screen design, etc.
To date, 773 has released the murder mystery Enfant Terrible, Cherry Tree High Comedy Club and its sequel, Aye-Aye Girls, and the visual novel Dead End Junction.
Source: The Game Website.
Across the web this developer has been referred to as Circle 773, Atelier 773, Atelier Nanami and doujin circle 773.