Manticore: Seishin Ikou Jikken Machi

Modern Japan—Anarchy City, a metropolis rampant with crime. Mimi Usazaki, a depressed college student attending therapy while trudging through her university life, one day gets caught up in a bizarre experiment. As a result, she ends up sharing her mind with her long-lost younger brother, Hyou Usazaki—a death row inmate. Now, she’s dragged into a deadly battle against other death row prisoners who were also part of the experiment…!? (Source: Kadokawa, translated)