DNA²

The enitial plot is the same... A female mercinary travels through time in order to assasinate a man who has rocked human kind in a devistating manner. Both assassin attempt more or less come to a standstill, as both girls arrive in a time-period where the chaos causing man is nothing but a nervious, innocent schoolboy: - In DNA2, Junta overpopulates the Earth - In Bokusatsu Tenshi Dokuro-chan, Sakura creates immortailty 

This Anime and DNA^2 are similar in ways. -The main character in DNA^2 barfs when he sees a naked body when in this he gets a nose bleed -The main character in DNA^2 is in a Dilemma on who to love, like in this film where there are many people to love. -The main character in DNA^2 gets a sort of charm sometimes, such as in this show, but it happens more often, and naturally. -The main character in DNA^2 gets an unexpected visiter from the future and begins to love her, like in this film. The Plot- Overpopulation...an issue 100 years in the future. Junta Mommonari, the Mega-Playboy who impregnated 100 women... and all boys... eventually his sons impregnated 100 women too... thus you see the overpopulation problem. Karin Aoi, DNA operator, must put a stop to Junta's dirty ways... but will she begin it? Will she fall in love with him on the path?Will she be one of the victims? Check it out as Junta transforms from his loser self with his "Girl Allergy"- to the mega-playboy everyone wants inside of them, but is it everyone? Will he really transform? YOU WILL NOT SURVIVE FROM CRYING IN THIS ANIME...if you dont watch it! So watch it! WATCH IT NOW!!! read more 

practically both mc have superpowers that attracts the women, and have fights too to help some woman.  

Both these anime series' main story is about a time-traveller from the future that is trying to change it from the past-line they travelled to. Basically Midori from Green Green and Karin from DNA2. Green Green is pretty grotesque with its ecchi scenes, DNA2 isn't like that at all. Nevertheless, both have a bitter-sweet ending that leaves you at awe and are worth watching definitely. 

both shows are about a guy who is allergic to women building his harem 

Both focuses mainly on a male and female couple, for a lack of a better term. While DNA^2 plot is more sci-fiction in a "modern era" B Gata H Kei is set in a high school. They both have a male protagonist that suffers or has trouble interacting with girls. -DNA^2 makes it a comical medical condition -B Gata H Kei looks at it as adolescences fumbling their way through romance. They both have a female protagonist that sets out for one specific goal, but ends up doing thing entirely different as they come to realize something about themselves and their counterparts. -DNA^2: Her goal is to kill the guy who overpopulates the world by sleeping with too many girls -B Gata: Her goal is to sleep with as many guys as possible to overcome her lack of relationship experience Both series eventually takes the viewer though an emotional ride though the highs and lows of romantic relationships. read more 

both main character can transform to be some kind of superman and their appearance will change to more spiky cool looking  

Same creator and similar character designs. Both are romance, I''s is alot more realistic though. 

DNA^2 and Golden Boy both have smart, considerate Playboy main characters! If you like seeing the girls fall for the guys then both shows are quite good! DNA^2 isn't episodic and centers around a set of main heroines while Golden Boy has a different girl each episode. There's also a bit more drama in DNA^2 just a heads up and an ass antagonist that comes in later on. 

Both have a main guy with an "allergy" to women, only Kinjirou nosebleeds and Junta feels like vomiting. 

Both of the original stories were written by the same person, Masakazu Katsura. They also happen to have the same feel to them, art-wise.