Petshop of Horrors

They're both about a supernatural shop; one that grands wishes to the customer and one that sells rare animals, but both the shops claim to fulfil the dreams of their customer. In the end both shops are there to teach the customer a wise lesson. 

it has the same old drawing stile and there bolth about fable animals 

They both have a dark and slightly older animation styles and feature darkly demented plots and horror twists. 

Let us delve into the human psyche and the horrors that entail. Both of these series tackle this element within the plot, in a manner which might be best described as macabre, and yet despite this being the best way to describe the manner in which the series delve into the subject matter, neither series is some slasher film as it handles the macabre subject matter in a manner that draws the viewer in rather than simply going for the gross out factor. So, welcome to the delightful horrors of these two series. 

Shady seller gives people sale of something special, but the people are taught a lesson as something inevitably gets out of control. 

These older horror stories are a quick watch and employ similar styles, but highly recommended if someone is looking for a classic of the horror genre for Anime. 

They have a similar atmosphere with both main characters to be quite mysterious. 

Both animes have a dark atmosphere that goes very well with the themes and storylines developed. Le Portrait de Petit Cossette's more romance-drama based, and on other hand Pet Shop Of Horrors is focused on mystery and human's psychological analysis. Either way, if you like dark animes that have the power to give you the creeps and stll be very interesting, now you've two good recommendations.  

Both Boogiepop Phantom and Pet Shop of Horrors depict the devastating effects of despair, and the grievous consequences that letting go of reality carries. These series feature highly troubled individuals who try to cope with the pressure of emotionally-taxing situations, and fail. In both, a supernatural entity has a highly dubious role in this process of mental disintegration. Boogiepop Phantom has a convoluted plot while Pet Shop of Horrors plays with a simple narrative frame; but they both explore the dark aspects of the human soul and do it with enthusiasm 

These two series feature a mysterious supernatural entity that preys on human flaws. Both Pet Shop of Horrors and Jigoku Shoujo deal with passing judgment and convey a very dark and depressing mood through the anguish-filled situations that desperate people have to face. They both delve into terrible moral quandaries and impose contracts that bind the contractors with the terrible consequences of their choices. In these series the supernatural elements serve as a device to exploring the heavy toll that certain decisions entail, blending insanity with a brooding feeling of hopelessness.  

In both stories, a misterious man reveals the true nature of his costumers in an unusual way (animals, in Petshop of Horrors; games, in Death Parade). Both are psichological, dense and episodic animes, that deal with morals and philosophy. 

Both gerneraly have the same vibe of human flaw. Each have humans with personality, or social problems that draws a dark influence to them, eventually giving them the power to destroy themselves with there own devices. 

Both are about ordinary people dealing with supernatural creatures. 

Both are creepy yet silly horror shows that both remind me of something I'd see at 2 am on some channel. 

Both stories introduce an enigmatic man who uncovers mysteries or delves into the psychological aspects and dark pasts and desires of the people involve in the case they are handling. In Petshop of Horrors, Count D, the main protagonist, uses weird and unusual pets to explore the dark sides of humans while in Housekishou Richard-shi no Nazo Kantei, Richard, the main protagonist, bring out mysteries to light with the use of the gems and jewelries. Both characters love tea and has a strong fondness to sweets. 

Short horror stories with cool visuals. While in both the horror itself is sometimes weak and more funny than scary, the situations are still enjoyable. 

Very similar feel, melancholic and eerie. Neither series is super well done in my opinion, but they both create a similar mood that I really enjoy. They also have similar aesthetics, with dark colors and sparse animation. I would describe neither as horror exactly, but they're both mysterious and somewhat creepy. Also both exploring the nature of being human in some way. I think if you like one of them, you'll like the other one as well. 

Petshop of Horrors - Both are mystery based, supernatural and both have a simular art style.  

Same idea of supranatural wishing shop and owner that isn't really what it appears to be 

Both are dark. Both are philsophical. Plus, if you sqiunt, Count D kinda has traits of both Raito and L.  

Pet Shop reminded me of Mushishi because of how supernatural creatures were mixed together with everyday, normal characters; the sort you'd see in slice-of-life titles. I suppose Pet Shop is more 'horrifying', while Mushishi is more relaxing, but there are definitely similarities between the executions of the two. 

Both are episodic OVAs which take narrative cues from the seminal series The Twilight Zone, where a single mystery/horror/paranormal concept is explored in a short parable, with the main recurring cast member being a charismatic narrator who is only loosely involved in the story. As is the tradition, the stories are often left open-ended and under-narrated, with part of the mystery and the lessons learned being left as an exercise for the audience. Both OVAs have well-defined, memorable, flamboyant visual style that balances right on the cusp of self-irony. It is interesting to see the JoJo style being used for this kind of content—it fits remarkably well and does not rely on the knowledge of the JoJo's Bizarre Adventure lore to any significant extent. Fans of this brand of horror-mystery will surely appreciate it even without being acquainted with the main JoJo series. read more 

Both stories are a bit morbid and dark. Pet shop of horrors contains more light humor but there similar in both art and the darkness of creatures. 

Both of an older animation style and demons-related plot, they have a similar dark, mysterious feeling to them; both with a big potential to make full-lenght series. Also, Tsunami somehow reminds Count D, the more so because they have the same seiyuu. 

both deal with customers and wishes... and how they can go wrong. 

Both have dark ambient and are mysterious. Also, they share some feeling of tragedy. While in Gilgamesh one fact is the main tragedy, in Petshop of Horrors there are many mistakes made by many people. Mistakes that cannot be undone.