Koroshiya 1 The Animation: Episode 0, Nido to Mezamenu Komori Uta Recommendations
Both are anime that portrait the bullying and the repercussion it has on the person. Both are older anime and have trippy animation as well as the narration. Both are dementia genre and as dementia anime tend to do, they have interesting plot twists and overall mindfuck. Both have violence as well as nudity.