You know me so well, Nagito! She is killed during Gonta's execution after a giant mechanical wasp emerges from her body.
However, it is also shown that though his good luck rarely manifests, it is immensely powerful in its own right, allowing outcomes that are nearly statistically impossible to occur, such as getting the Escape Switch from the item machine or surviving his near-execution.
He has various copies of himself throughout the academy and will punish anyone that attempts to attack him or breaks the academy's rules.
Others will focus on the differences between them, such as Nagito being fine with the killing while Kokichi is seemingly fine with them but secretly despises them.
Before his death, Chihiro leaves behind a laptop containing the Alter Ego program to help the others, thinking he was not going to survive.
She was killed by being repeatedly hit over the head with a swimsuit filled with pebbles by Sato.