If you're looking for anime similar to Keina Suda: Darling, you might like these titles.
The official music video for the Vocaloid song Hana ni Kaze, by the producer Balloon.
songs written by the same person and animated by the same person ; same melancholic vibe, however one is sung by a vocaloid and the other by a human. I think that if you'll like one, you'll love the other as well because of their similarities in terms of instruments, beats, but also in terms of animation.
Shiki ends up keeping a black cat while Mikiya Kokutou is out of town. Meanwhile, Ririsu Miyasuki, a student of Reien Girls’ Academy, suffers from the loss of her best friend who committed suicide by jumping off the Fujou Building. When she tries to kill herself, she encounters her classmate Asagami Fujino, who has psychokinetic power.
The song tells the tragic story of a man who, as an everyman in society, has been living a hopeless and hypocritical life "killing" his true self for the sake of livelihood.
The two of them, all alone at home. All alone with her father's corpse. Memories, ideals, and reality all sink beneath the muck. Everyone is alone. Everyone is in solitude.