Ai ga Iru nara Kimi de Ii

High school student Tokita Natsumi cherished his girlfriend, Momose Ai, above all else. However, one day, Ai is stabbed to death by Yomiyagi Nozomi, who had previously attended the same juvenile detention center as Natsumi. Stunned by the sudden turn of events, Natsumi is called by Nozomi's name, but her voice sounds strangely familiar and gentle ?! From then on, Ai and Nozomi's personalities begin to switch places within Nozomi's body. Caught between his beloved girlfriend and the murderer who harbors a deep hatred for him, can Natsumi still continue to love her ?