I’ll Get Serious After I Die manga, Shinde Kara Honki Dasu 死んでから本気出す
Takai Sena, a victim of relentless bullying at her high school, wishes she could die and reincarnate into another world. One morning, after pushing a neighborhood cat out of the way of an oncoming truck, she gets her wish, and wakes up as a ghost.
Accompanied by Familia, her so-called spirit guide, Sena is tasked with scaring the living and collecting the fear-essence they release when frightened. In doing so, she quickly discovers an extraordinary aptitude as a ghost, and finds a newfound sense of power and purpose in the afterlife.
Vowing to only scare those who she considers “evil,” from abusive bosses to her own past abusers, Sena soon finds that confronting her own trauma may be the scariest thing of all.