Otonashi is the main protagonist in Angel Beats! He has a caring personality and tries as hard as he can to help his friends.
When he was alive, he spent most of his time with his sister in a hospital instead of studying and making friends. After his sister's death, he aspired to be a doctor to help people. On his way to take the entrance exams, the train crashed. He and several other people managed to survive the crash itself, but they were sealed inside the tunnel. After a week to ration their remaining food and water and tending to the sick, he decided to donate his organs so he can help others before he dies from his injuries. His last act of kindness motivated others to sign their life insurance card. Moments later as the tunnel is finally opened, Yuzuru died from internal bleeding.