Every case in the games has a reason the protagonists isn’t targeted. <!THH:

Chapter 1 - Leon was attacked by Sayaka Chapter 2 - Mondo was angry at Chihiro Chapter 3 - Hifumi was easy to manipulate Chapter 4 - Suicide Chapter 5 - Mukuro was killed earlier

DR2:

Chapter 1 - Imposter took the stab for Nagito Chapter 2 - Mahiru knew the killer of Fuyuhiko’s sister Chapter 3 - Mikan was using Hajime as an alibi Chapter 4 - Hajime doesn't have a built in clock Chapter 5 - Hajime wasn’t the traitor

V3:

Chapter 1 - Shuichi did not set off the camera Chapter 2 - This one Shuichi could have been targeted but Ryoma was an easier kill Chapter 3 - Shuichi isn’t a girl Chapter 4 - He wasn’t going to kill Kokichi Chapter 5 - He was not involved!>