I Am Mentally Ill, and the Queen of Rage

The protagonist was killed by a madman for stopping to watch the commotion. After being reincarnated, she discovered that she'd become a girl, and a lunatic to boot. She was just like a normal person most of the time, but when madness took hold, her mind filled with a desire to destroy. Step by step, she learned to master her anger, becoming the terror of every beast and enemy.

I tear apart the morning light and crush the silence all around me, letting madness blaze like a fire in my veins. You watch coldly as my silhouette falls, so I smile and drag the world into the maelstrom.