Gyo

Same Western styled Horror and walkers (albeit different styles). 

Same author, bizarre stories, oddities, greasy terror. 

My personal reaction when thinking of both of these series is mental vomit, yet not in the manner one might be expecting. I'm not talking about a poorly made piece, but the mental vomit one gets in regards to the horror genre. Both series delve into the horrors of man kind, but also abandoning of all hope. Well, it is horror after all. 

This is one of those horror animes that takes you on a rollercoaster ride without telling you you're on one. You will think it's all normal until shit actually unfolds now you can or could've seen clips from this show around the internet you most likely heard of this anime. For those who have seen the clips but never watched the show give a watch and see for yourself. It's good not the greatest but still godlike nonetheless. 

Both OVAs deal with predators from the sea going to war with humans. While "Gyo" takes a more surreal and horror'esque approach, "Blue Sub No. 6" plays it rather straight. 

So similar to each other in the eroguro dept. and the thing that possess the human transforming it into something grotesque, also the romance between the two is tragic... 

Both had a girl trying to reach a person through an apocalypse with the help of someone they've met. 

They both depict a failing Japan in a similar poor plot. 

Both movies made by the same studio, CG looks pretty decent in both. 

"Gyo" and "Adventures in Beauty Wonderland" are standalone titles that use wild imagery of fictional creatures in order to disturb your mind. A similarity between these two works is that they steadily becomes more and more confusing as they progress on, with both being very crazy in general. 

"Gyo" and "Agitated Screams of Maggots" both showcase disgusting creatures suddenly appearing in society, people's fear of them, as well as a certain level of gore. 

Focused on epidemics. 

Plagues that alters the human body. 

Both Anime have a interesting horror concept one you have killer insects and the other you have killer aquatic animals that can breath out of the water but both have kinda weird thing also involved I don’t want to spoil it so if you enjoy horror and creatures like the movie bats, rats, birds, etc then these two anime are for you 

Both are some of the funniest anime made in existence. Both anime are basically stuff that you would watch while doing MST3K-style commentary. 

Land lubbers are invaded by malicious sea dwelling creatures. 

Although the messages offered by the two are different, there's something slightly similar between the two as concerns the style of splatter scenes that both provide, such as the humans' behavior for the respective situations.