Girl WHY THE HECK are you suicidal now?
I mean, that's the perfect antagonist to Satsuki's modus operandi of always sparing a life, and it is a bit different from Prez saying certain people deserve to die and being a serial killer. Komachi probably believes so strongly that if someone is supposed to die, then they should die, interfering in things because you want to is wrong to her — it's not saving a life, it's doing something unnecessary. And given how much of a pushover she is, I think it's within her core beliefs that we shouldn't act in our own volition to change things and that Satsuki going against this should be sabotaged.
She could be someone who believes in the supernatural about to have a psycho-breakdown, but after we've been shown the two extremes of saving a life and taking a life, not acting against what the mysterious force going around and causing deaths seems to be Komachi's point, and she'd become so certain of this that she will go to all lengths to make sure that those deaths that have been postponed actually happen — because "that's the way it should be".
Girl is low-key nihilistic ig, but there is something evil behind her conviction that she should be the one to kill since the deaths NEED to happen (it doesn't excuse murder, just like the StuCo's killing spree made no sense).
Komako Komachi is what would happen if Nietzche and Satan had a child and it became a japanese high Schoo girl.