I'm Really Ordinary

Am I a killer? No, I'm just an ordinary high school student. ??? There is another soul in my body? "Can you give me control of my body?" "Huh?! My body? Are we the same person?" "Almost the same, but you are my separate personality." "Then... I leave it to you, take good care of my body." "Don't worry, this is my body too." This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.