C³

Both have characters with supernatural abilities which are very similar to each other. 

Bright colors, a chaotic plot line along with a chaotic cast of characters. 

Both of these shows are about artifacts. Dragon Crisis! has them in a more positive light, while C³ has them in a darker light. But some of the objects actually have a life of their own. 

Both shows have people fighting using, or being, cursed instruments/tools. They also look cute at times, and very violent at others.  

The two series left me with the same feeling, but they were both also dark and ecchi, and yet there are plenty of series out there which have these themes. Specifically, in this case we have a group of individuals drawn together to solve the problem of being a “weapon” and the wonton destruction of the world which may end up resulting from the being of a “weapon”. What I mean by this is possibly better understood though if one has watched one of the two series. 

Girl comes out of a strange object with super powers Boy conveniently lives alone and girl stays with him Ecchi elements galore Plenty more to list but you get the idea. 

-harem -each show has a clear enemy with two distinct teams fighting against them -girls with cool superpowers -interesting and attention keeping undertones of romance 

In both shows there is a fighting male protagonist and a female companion who can change into his weapon [Yachi and Konoha=Coud and Ren]. 

Same art style, different genres. 

Both muchachos (male lead) have chiquitas (female leads) living with them. Both muchachos are nice guys and may look vulnerable, but they can can fight. Both muchachos always have their butts kicked when their chiquitas are pissed. Both have panty shots. One is limited to a three-way harem, while the other one has a two-group harem—one group in the dorm and another in the student council. One muchacho relies on the other chiquita to be his weapon when fighting, while the other has a special ability to fight when push comes to shove. In one anime, it is the harems who come into the muchacho's life, while in the other, it is the muchachos who come into the harems life because the school that was once an all-girls school became co-ed and the MC is looking for some perverted action... at first that is. In Maken-Ki, the muchacho is up against fellow students who want to duke it out on the disciplinary committee, while in C³, the muchacho is up against supernatural beings. Maken-Ki's panty shots are more intense than C³'s. read more 

both have many girls both have kickass women both the boys have special power both main characters of the anime have dark past. both have one tsundere character beside them  

Both Bakemonogatari and C³ are similar in a number of ways, in some ways the art style is similar, in other ways the dialog between the characters seems similar and both use teenagers with superpowers as an allegory for real life problems, in that reguard C³ has better action scenes and characters while Bakemonogatari has better art and dialog, in my opinion of course. If you enjoy one you should enjoy the other. 

Although the story is different, it features a main female character, who is cursed and have supernatural powers to fight off opponents or monsters. They are not seemingly hostile, instead they are friendly, having emotions, and having a cutesy appearance. They sometimes fight alongside with the boy, having some firepower or some backup to help defeat their target. C3 is basically a school comedy, that fights other cursed people, while Black Bullet is a post-apocalyptic setting, fighting monsters.  

Same mix of cuteness, erotic moments and bloody violence with only one male lead and plenty of different girls, from little ones to young adults. 

Both start off as cute moe comedies before switching to a horror style. 

Same Genre : Action, Ecchi, School, Supernatural Male protagonist surrounded by females. In both shows there is a fighting male protagonist and a female companion. If you like supernatural anime, this anime is recommended for you .. 

Artificial life. To everyone else, they're just artificial lifeforms, but to the main character, the girls are in fact alive just like everyone else, not the tools and weapons that the rest of society has deemed. Let's not forget the harem element some are looking for, along with the bright colors and artwork which utilizes detail in a similar manner. The girls also struggle with what it means to live by the idea they're not simply tools. 

Both Anime contain bright blue haired girls who don't know how to fit in and the main character helps them to learn to fit in and be as normal of a girl as possible. 

If sending a part of your almost-human-loli harem is quite a hard concept for you to grasp, these will help you understand it. 

Both are Action, Comedy, Supernatural, Ecchi, Harem, Mythological, School shows centered around a Tsugumono meaning an object or tool that gained life thanks to the prolonged use and influence of humans and a curse which turned into a cute blue haired loli.  

A nice guy acquiesces to the whims of a cute tsundere loli and a heart-warming friendship is slowly but surely built. 

they both give off very similar vibes. the main character is a unique person in their respective worlds. Ai is half-human half-gravekeeper. Haruaki is the only person that is immune to curses.  

Both follow a main character who were raised as weapons trying to adjust to the role of a normal person, but having to battle with the guilt of the sin committed in their past, which is a factor in hindering this goal. Violet and Fear are very different personality-wise apart from not understanding social norms and the general tone and execution of Violet Evergarden and C³ are also contrasting. However, if you particularly like the concept of a 'monster' learning to become 'human', then both series should interest you.  

Besides sharing similar genres and having great art, both shows have female characters who are weapons that are trying to adjust to society. 

lots of people may think i am nuts for saying these two a similar but... overlord and c3 both have the harem aspect in the anime (more noticeable in c3) but in overlord, there's more action, although in c3 there's still some action but it's not 100% action like overlord. c3 still has quite a bit of action in it though. so overall, overlord is (c3 minus ecchi) 

Both are harem, and contain some ecchi elements. I found both main characters a bit similar too. Both have a good animation. So, if you like one, I think you'll probably like the other.  

Both of these anime are about a girl adjusting to a 'new world' and being taken in by our protagonist (also a boy in C3). Both have a running romantic theme. Both of the main plots of these anime are reliant on the acceptance of the main character of the girl's odd quirks (like Rea being a zombie and Fear being cursed are quirks) C3 is slightly heavier than Sankarea and puts more focus on side characters. This anime is also quite action packed. 

Starts off seeming like a common anime trope, but quickly turns dark, gritty, and very awesome. Violent battles, great artwork, and cool characters. 

Highschool DxD is like a repeat of C3's very first episode, generic harem fanservice bullshit, but with bigger tits. Will this stay that way or will it suddenly become awesome like C3 did? The former is more likely. 

Mild shounen spins on the 'magic girl' type. The leads in both are male characters who are pretty much average, using the abilities of the 'magic gilrs' sidekicks in order to save the day as they face off against threats that don't need to concern them personally - trouble seems to follow the famales. 

Both stories revolve around artifacts containing powers. The main character is a male. 

Both of these Anime has a dark side to their story, not to mention they are also harem. 

Both series have people with weapon forms. 

In these two anime, the girls are stronger than the boys, and usually the boys are only assistants to the girls. 

Both main female characters were "born" as an object and hosted in the protagonist's house. Similiar humour and situations. 

A very kind guy and a cute, nice but slightly stubborn girl join forces to deal with supernatural threats and problems. 

Aside from the obvious loli tsundere female leads, both series alternate between comedic slice-of-life scenes and dark, intense fights, which actually give off pretty similar atmospheres. 

Both have a same style. Both have a main charachter with blue hair. Both are with "non-human" girls who learn to behave like a human. Both are action , comedy , ecchi. 

The main guy's father is always away from the house and always sends odd things to the main guy and the thing that the father send turns into a girl after the main guy opens it...Yup... exact same scenario. 

Both are shows that have lots of ecchi and shift frequently between comedy and drama.