Kyougoku Natsuhiko: Kousetsu Hyaku Monogatari

Episodic tales of the supernatural, presented with a unique and distinctive visual style, and tied together by an enigmatic main character. 

These animes are stories about mononoke, based on Japanese legends and rumors. Main characters are grim and mysterious (I guess the only exception is Momosuke-sensei) and they deal with evil spirits. And, in both animes, the truth about reasons of birth of mononoke is sometimes much more violent than mononoke’s actions. Besides, both of animes have unusual, but not similar art style. 

Both series have quite distinctive art style, though not same. Mononoke use brigter colours, where Kousetsu Hyaku Monogatari is more muted and use darker colours. In both series story revolves around supernatural in form of human depravities or ghosts or other creatures. Both are heavily influenced by japanese folklore and myths. Both are set around edo period of Japan. Both are for older audience in tone, though Mononoke is not as violent. 

If you liked Mononoke, then you my friend, for sure should try out this series called Hundred Stories. The series revolves around a writer who is looking for ghost stories all over the world which he can write about, in the journey of which he comes across three entities who indirectly guide him through his venture, simultaneously fulfilling their own purposes. Mononoke features an unnamed entity who goes by the title of the "Medicine Seller" who wanders around the land casually, coming across various spirits whom he exorcises one after the other. 

Both series are supernatural crime Investigation anthologies in which supernatural entities solve cold murder cases (Mononoke: Medicine Seller, 100 Stories: Group of Specialists plus MC). Both are set mainly in the Edo period. Both have a distinct expressionist art style, albeit not the same. Both touch themes too dark and taboo for most anime, e.g. abortion (Mononoke), necrophilia, paternal incest, and cannibalism (100 stories). Both have skillful story telling with good twists and creative ideas. Mononoke's cases span several episodes, whereas 100 stories is episodic and solves all but one cases in a single episode. Mononoke is the better series, but both scratch the same itch for the viewer. read more 

Tells a tale for each episode. Both on a common theme of dark and horror. Jigoku Shoujo more about cursing people and having revenge. While Hundred Stories is about folk lores. These are told in mostly episodic stories that can be self contained, rather than serialized story telling. While Jigoku Shoujo (Hellgirl) has an over arcing plot, it isn't really the focus of the series. 

Pretty dark has similar story lines 

Both focus on punishing evil people,has lots of dark visuals and suspense in it and also nice art and character designs and psychological shit in it too. 

Protagonists uncover hidden story and gruesomely slaying people who did evil deeds. Very dark themed and gruesome. Supernatural monsters and use of edo japan period talismans and rituals.  

Both series deal with supernatural based on myths and legends, both are for older audience as they deal with more complex themes like morality and are to some extent quite violent. Petshop of horrors has little different art style, though it is similarly darker, stories are set in present day (or at least present day at time of creatiion of anime) while kousetsu hyaku monogatari is set in edo period. 

Both are very dark horror anthologies with elements of Romance and sexy undertones, following a grounded protagonist (Cop and writer respectively) encountering a supernatural individual with mysterious origins (or group of thereof) and getting involved in numerous, often tragic, paranormal incidents based on mythology (Requiem is specifically Japanese, Petshop takes from all cultures around the world) 

Both stories feature the tragic ends of malicious people who harm others for their own selfish gains. However, unlike many other moral-of-the-story horror tales, these two do show the various moral dilemmas of any situation. There is sometimes no true good or evil. Besides that, they both share distinctive art. In Ayakashi, each story has its own art style to fit the tale. In Hundred Stories, it tends to be surreal, with stark colour ontrasts. All in all, it's not your basic run-of-the-mill Anime art. 

If you have a taste for Japanese Ghost Stories or Japanese Urban legends, then this series titled Yami Shibai is a perfect recommendation for it. Each episode of this series deals with one separate ghost story from Japan, and the runtime of each episode being approximately 05:00 minutes. Compiled in three separate seasons, each season carrying 13 episodes; Yami Shibai is a perfect must watch especially if you want to spend your weekends alone and are looking for thrills. Hundred Stories is a similar series in the nature that each episode of Hundred Stories encircles a separate ghastly happening in the ancient Japan. 

Both are fairly disturbing and graphic horror anime around a diverse team of supernatural detectives investigating mysterious murders and exorcising demons to solve them. Both anime start out episodic and switch to the background story of the investigators in the 2nd half. In both, demons are sort of materialized negative aspects of the human subconsciousness and dark emotions. The main difference is the time period, in Enema it's contemporary and Kyougoku Edo era Japan. 

Both Boogiepop Phantom and Hundred Stories share a creepy and strange mood. They contain many mysteries that need to be peeled back in order to grasp the truth of human nature. If you like strange creepy anime full of strange and fascinating characters, these are the shows for you.