Complex sentence: He enrolled in the philosophy department of Tokyo Imperial University, but left without graduating in 1907 to form a literary group with Kinoshita Rigen, Shiga Naoya, Arishima Takeo and Ogimachi Kinzaku called "Jūkokakai" ("The Fortnight Club").
Split into simpler sentences: He enrolled in the philosophy department of Tokyo Imperial University, but left without graduating in 1907 to form a literary group with Kinoshita Rigen, Shiga Naoya, Arishima Takeo, and Ogimachi Kinzaku. They named the group "Jūkokakai" ("The Fortnight Club").