While watching the anime for this manga Tokyo Ghoul instantly came to mind. To avoid spoilers i'll just say both main characters are in some what similar situation in addition to their personality transition.
Parasyte and Tokyo Ghoul both involve male protagonists who wake up one day... different... One turned into a ghoul... while the other simply had an alien for an arm. And by alien, I mean a life form that has 100% control of the arm for most of the day. Coexisting and dealing with others who are similar to them, both characters have to live in the same world... with a completely flipped perspective.
Tokyo Ghoul is more supernaturalesque/fantasy and more gritty
Parasyte is more scifi-ish and psychological
Both have action and they are both great reads. Parasyte though is not a bishounen read. It's not pretty... or rather... it's from the late 80's early 90's.. so... it's much much more realistic.
I liked Parasyte a lot more than I did TG, but both are great great reads. :D read more
Although the stories are different, Kiseijuu and Tokyo Ghoul shares a familiarity with supernatural horror. The main male protagonist's life changes forever after one faithful day after coming in contact with a supernatural being. And from that experience, they inherit traits that no longer makes them fully human. Throughout both series' perspective stories, the MC struggles to at times to figure out how to deal with his newfound life. At times, they face obstacles but also find new hope. They must also accept who they are as well as realizing the truths/consequences of what they have become. I recommend both series for anyone interested in supernatural horror. read more
after reading both i would say tokyo ghoul is inspired from Parasyte
more over i would go ahead and say it is a rip off (tokyo ghoul: re is a different story)
-main guy becomes a HALF parasyte/ghoul
-there is a Anti parasyte/ghoul police force
-both the police force engage in a all out battle against parasyte/ghoul
-majority of the parasyte/ghouls get wiped out
-both have grotesqueness (limb, head, etc torn into pieces)
-endings are a bit different coz tokyo ghoul had to continue....BUT both are GOOD READS
In both, there are male main characters, whose normal lives are interrupted by terrible twist of events. They are both becoming something between a human and a monster, and are struggling with their fate and their own new selves. Kiseijuu and Tokyo Ghoul share a great amount of bloody fights, well done character development and mystery. I would definitely recommend both of them.
While the story of the main characters is slightly different these two are very similar manga and the anime adaptions will also be similar. Both are about a boy who is suddenly met with a strange being in their life and must come to terms with the new abilities that come with this fated meeting. Both feature the struggle of each person's morals and beliefs as they come to accept what they are and use the new abilities they posses to fight a foe. Both are especially violent and gut-wrenching seinen manga with very dark themes and people being split in half and eaten.  read more
Both are about an ordinary high school boy who acquires some kind of evil unknown power and wants to get rid of it, until it accepts it at some point. Both have a lot of gory elements as that "evil power" has the tendency to kill people.
An ordinary high-school/college student gets turned into a monster by an unfortunate accident; this pretty much mirrors the main plot of these two seinen mangas. Both also deal with how the main characters struggle to preserve their slowly declining senses of humanity as more things happen due to their new nature. While I enjoyed Tokyo Ghoul more, both mangas are nice reads.
Tokyo Ghoul obviously took a great deal of inspiration from Parasyte, from the 'monsters' who need to eat humans to survive to the human who becomes part of both worlds (sort of...) though Tokyo Ghoul has more of a culture with its monsters as opposed to Parasyte, where the monsters don't really have time to establish a culture that we see much of.
Those familiar with Parasyte would view 7 Billion Needles as something of a rip-off, should they read it. An eccentric alien entity comes from outer space, merges with the lead and slowly-but-surely comes to be friends with its host, as they battle together against other alien enemies. If you're experienced, you've read it all before.
The first two volumes aren't bad - the characterisation being solid enough - but the last two turn it into a nonsensical mess that would most likely leave you with a desire to have re-read Parasyte instead.
In terms of the 'merging' itself, 7BN has more in-common with Birdy than Parasyte since in both the leads die and need to rely on their new companions to survive. However, since Birdy has a human form all of her own, the relationship development isn't really very similar to what 7BN has to offer. read more
Both stories involve creatures which take over people's minds and bodies and can morph them in monstrous ways, and a protagonist who manages to retain his human personality despite being one of these hosts. Both protagonist's have to deal with this fact while keeping their identity secret and struggling not to lose their humanity.
Both characters go through a change in their hand due to an unknown source. The the characters go through a lot of psychologically damaging events because of this change
Both mangas contain plenty of gruesome elements,as they are both in the horror genre.
They gave of quite a similar feeling in my opinion.
While Kiseijuu involves people who are infected by something alien and Ajin seem to be transformed humans, there's a common thread of people trying to survive in a brutal world where they don't know who they can trust.
Similar premise where the main characters are on the run with an unknown entity within them. Their normal peaceful lives come to an end and they're thrown into a kill or be killed situation. The characters are somewhat similar as well because they're in a moral dilemma and have to choose whether to support humanity or the unknown entity.
Despite the temporal distance, both mangas are very similar by the feelings that they get.
Violence and particular design must be surmounted, because it's beyond that is situated the real treasure : a beautiful thought on the human kind.
The heroes of both series, although different in motivation, have the same goals, and that is to exterminate the creatures that push their mankind to fear and despair with the help of their special powers.
But there is more than that; both series revolve around the question of one's humanity. While SnK takes this on a subtle approach, Kiseijuu is direct to the point it is the manga's main theme.
Both stories are about a teenage boy who's right hand turns into a living being (a weird monster/alien... thing and a cute teenage girl), which he must coexist with while keeping it a secret from other people. Other than that, they're completely different. One's an dark sci-fi body horror story (Kiseijuu) and the other is a wacky romantic comedy (Midori Days).
Okitenemuru and Kiseijuu involves mysterious beings that becomes part of human society. The main protagonist gets involved in an incident where they gain a special attribute that changes their life forever. Throughout the story, there is violence, death, and mysteries that is unsettling as we learn more and more about certain strange circumstances.
Both Manga are about parasites, which invade the human body and make them to overpowered monsters. The source where those parasites come from, is unclear. Both Manga contain a lot of gore and nice illustrated body horror.
Both series deal with shapeshifting lifeforms (in Inugami's case wolf/dog deity/things? and in Parasyte alien beings) that come to earth and wreak havoc, the stories centering on one lifeform that forms a friendship with a human boy (though Inugami's bond is more emotional and heartfelt), with the obligatory girl pal tagging along. Both series are highly recommended for the mature audience who can take bodies being ripped to shreds and appreciate a well developed seinen piece.
When part of your body belongs to another entity, where does the line between you and this other existence get drawn? - That is the question Heads and Parasyte ask.
In Heads, its lead gets shot in the head and is saved from his coma by becoming the first ever adult brain transplant patient. In Parasyte, the arm of its lead gets replaced by an alien. In both the once calmer, more timid personalities of the leads gradually change until they no longer can be recognized as who they once were.
Heads in particular is recommended to those looking for psychological thrills with a difference. It deals exclusively with the small but significant differences that separate individuals, and how everything can change so easily. read more
Scifi stories with horror elements. Both are thought-provokingly psychological and highly suspenseful with great drama and interesting storylines, and they both also contain deadly enemies and extreme violence.
If you preferred Tanabata no Kuni then by all means proceed and read Parasyte, which is Hitoshi's praised work -- also contains SF / Horror elements.
Vice versa -- Tanabata no Kuni is basically a copy of Parasyte. Not one of those shameful copies, but similar in many traits, albeit certainly fun to read.
Historie is written by the same artist. They both got a really good story.
Only the genres are different. Historie is a Historical manga when Parasyte is a sci-fi manga, but I bet you'll like this one too!
Both mangas have a similar dark deep style and a draw style alike. Hunter x Hunter's Chimera Ants Arc is really similar to Kiseijuu. Also Hunter x Hunter's character Menthuthuyoupi is based on Kiseijuu's Gotoh.
Whilst one is a novel and the other a manga, what these two works have in common is that they both revolve around humans who have been infected by parasites. Each showcases fierce battles between human hosts, with Zettai naru Isolator taking a more superpowered approach. Both works are completely gritty and enjoyable.
Kisejuu is similar to x-gene on how the main character has some sort of monster inside of him and how it enjoys killing. Both characters fight against that nature at first but then begin to use it to protect the ones close to them.
Parasyte is a masterpiece and does not need much introduction, but Igyoujin Oniwakamaru is underrated IMHO and although it probably has more in common with Devilman, I still think the recommendation stands. In both cases, the protagonists get "infected" and once they come to grips with the situation, they gain impressive battle powers. Not that they have a choice anyway, plus their worlds start to crumble down. The host and foreign entity eventually collaborate and even start to understand one another. Oniwakamaru ends abruptly whereas Parasyte somewhat drags on. Both titles are gory but Oniwakamaru much more so.
Both involve main characters becoming hosts for alien-like organisms. These sci-fi manga explore human psychology and the gradual changes of our hero's personality (although Guyver is more action oriented).
I honestly can't believe these two weren't recommended for each other when i was reading one i thought "wow these two are rather similar"
both have high schooler sharing body with something not human, both fight their own non-human kind both main characters gain power while merging with each other gradually both of the main characters start to see the world differently and feel non-human their personalities seem to change and both have subtle romance
While the art in Uzumaki is more terrifying than Parasyte, they both balance horror, romance, and other story elements perfectly. They share the general theme of body horror while going beyond generic gross-outs and mutilations. They're both truly creative with mutations, making them interesting and sometimes terrifying.
Both manga feature main characters that find themselves caught on the opposing side of supernatural enemies of skill and power far beyond theirs and both use quick wits and brilliant tactics to defeat their monstrous adversaries. Great battles with brilliant tactical execution featured here, something most battle manga seem to lack.
Blood, gore, horror, strange beings which can eat humans from the inside out.
Che graphical style is very similar, but the premise is a different one: BioMeat Nectar focuses on survival in
a devasted world against unintelligent beasts, where as Parasyte the main hero fights against intelligent invaders living undercover.
Strange, foreign creatures forcefully make human bodies their hosts. Parasites are not as self-aware in Manhole, and Kiseijuu evokes a more thought provoking response to the readers due to questions about morality and humanity.
It's the same in that they both have something invade the body in which they can somewhat communicate with and the main character struggles to keep his humanity. Keep in mind, the art is not as good and its more grotesque but thye story is good.
Despite the title, Zombie Hunter is more like "Parasite Hunter". Both series contain parasites that take over the human body, are difficult to kill, and are weak against fire. Parasyte is much better, but Zombie Hunter is a quick read and certainly beats out Parasyte in the art department...
Both stories are AMAZING and refreshing psychological thrillers drawn in a realistic style. Parasyte (64 chapters) is an epic in length compared to Blue Heaven (24 chapters) and the plots are pretty different. But they're both masterpieces of equal caliber in my eyes.
With gritty style and awesome story lines both Battle Royale and Parasyte caught me from the start and refused to let go. In both stories the characters are faced with seemingly hopeless circumstances that they desperately struggle to change. Battle Royale and Parasyte are fundamentally different in that one features an epic survival game while the other has parasitic aliens invading the Earth but both are amazing mangas!
A high school boy is infected by something strange, and forms an uneasy alliance with someone to fight and kill other infected people. His "condition" evolves. His girlfriend knows something is going on, and is upset at his secretiveness.