Spiral: Suiri no Kizuna

These anime both has a similar supenseful approach in solving mysteries by out wittting their opponent. Both animes have their characters think of detailed and ingenius plans. Both keeps you guessing.  

Both include mysteries that are fun and interesting!!! 

The anime style is Gothic, the genre is mystery, specifically dealing with a high school detective. There is a lot of angst and wonderment about whether the canon characters will live or die. 

They are both detective anime, but the mysteries in detective academy Q are more solvable and intriguing whereas the problems in spiral are more on the unreasonably difficult side. 

The both series share the same kind of intenseness and both the main characters are cool and level-headed (plus quite good-looking!) males who will constantly get into lethally dangerous situations from which they survive only by thinking. 

Both series revolves around the theme of detective fiction in a school life setting. Both series' main female protagonist have similar personalities with the common passion of wanting to solve cases, helping others, and being a curious girl. Both series contain drama, comedy, and occasionally emotions that defines the moral of some mystery cases. 

they both include figuring out what happened to their brother, and about destiny and fate and stuff 

The action part of both series centers around mind games and logical strategies with surviving/winning as a goal. Also the enemies are prone to changing sides, though their motives become clear eventually. 

One of the things popping into my head as I watched Phi Brain was how this particular series kept reminding me of Spiral. Still, I found myself left with the feeling Phi Brain may have been inspired by Spiral, which is an older series that has, I feel, over the years, fallen a bit by the wayside. But, effectively, both series involve the mystery genre. Yet, they also fall mildly into the crackfic genre by taking things in an unusual direction the viewers don't expect, definitely pushing the willing suspense of disbelief in both, yet in a good way. 

Both anime are mystery and about crimes. The characters and stories are great. There are also some comedy scenes. 

These are both detective anime with little problems to solve that let the main detective come close to a large mystery of him/herself. Also, these series have people that seem to be cursed by fate. 

Similarities: -Theme of 'man-hunt' seeking revenge - a manipulative 'antagonist' - confusion on who really is the antagonist in which there is a clash between moral and logic - Cool detective work - characters varied from avoiding, accepting and fixing the past - And, unfortunately, the ending is what really connects these two animes together... 

Both families have been born into a cursed fate. 

Both related to young detectives solving mysteries.....and overly enthusiastic female side kicks which serves as comic relief in their respective series 

Solving mysteries like a pro. Both of these anime(s) are unique and rare little gems that some fans might miss out in the old school days and the current era. Regardless, these two anime(s) offers something special for those who are into mystery, a bit of thriller, and detective fiction. 

Both stories have the same kind of intrigue that make you keep watching... Mysterious characters with even more mysterious childhoods and superpowers!! 

They share a melancholic atmosphere and a dialogue-driven narrative. Both are characterized by well-crafted puzzles, a contest of wits between male and female characters, and the fact that the anti-hero is a cute schoolgirl. 

Mystery thriller, keeps the person watching in suspense. It also deals a lot with the events of the past and their relationship to the present and the future. 

Both contain a wide variety of characters. Involves a mystery. Subtle romance between the protagonist and another character. Both protagonists are incredibly intelligent. 

Both are shows with huge overarching mysteries. Tempest is much more of a psychological fantasy while Spiral is more of a true mystery anime. Both feel like a game with characters facing off in battles of wits, and are full of twists and turns from the start until both of their epic finales.  

Even though these two series are quite different in many ways, they both deal with a group of special/different children whose past and future look kinda gloomy and the present is full of mystery. Both anime raise a lot of questions at the beginning which will keep you watching till the end. (The ending of Fantastic Children is much more satisfying though - in terms of answering the questions it raises.) And they are both fun to watch.  

Both series has "cursed childen" and annoying female sidekick Although Black Bullet is a little bit fantasy, while Spiral is more to reality 

The theme of mystery is something hard to ignore in both series in both of these detective fiction series. Comedy and drama are also present as well as some emotional moments. Both of these series are a must-see for anime fans into the mystery genre. 

Both series involves mysteries with a mix in of thriller-like themes. Detective fiction is one of the central themes of both series as the MC and his partner try to solve various mysteries on a daily basis.  

Both anime are mysteries. For main character Takizawa, in Eden of the East, it is the "Selecao" and for main character Narumi, in Spiral ~ Lines of Reasoning, it is the "Blade Children". Takizawa and Narumi are alike, each with a "devil may care" persona. They also share a style of humor that is very sarcastic and dry. Both come off as cool, confident and nonchallant, and withhold pertinent details from companions while resolving mysteries that will, I assume, inevitably lead them to their goal. 

They are both really similar in that the main character is intelligent and cool!!!XD & they both dont care about anything, nor do they have many friends in the beginning. The ending is quite similar too! it ends up that both animes doesnt explain at all everything and makes you think there will be a second season. 

Both are, for the most part, episodic until the last few episodes- which is when they both explode into awesomeness 

Both are thinkers that involve cops, violence, and having lots on the lines and both have a wide array of character types 

In both main character has an older brother, who is involved in the mystery of the plot, whose whereabouts are unknown for some time and with whom the main character is sometimes compared. Also, in both the names of those older brothers sound alike. 

They both have rare diesease that make people diffrent, surronds detectives and killers. 

The theme of detective fiction comes to play in both of these series. Also, the main protagonist is intelligent has an aid there to help them when in need (the main heroine). Additionally, there is a psychological thriller like feeling in some of the cases that gives the viewer the question of doubt. Drama and small hints of romance are also present.  

Spiral and X does connect a little bit, since Ayumu Narumi and Kamui Shirou was created as a savior of people, not to mention their seiyuu is the same, Suzumura Kenichi. It is like that even Ayumu doesn't want to believe about his fate as well as Kamui, fate will still make a way for them to do what fate told them to do so. They also doesn't get the point of what is destiny and that the two heroes could only change the future with their own choices and Ayumu's sister-in-law, is look up to be like Kotori that believes that the future is not decided in which the two of them believes about... read more 

Spiral: Using detective skills to solve things. Spice and Wolf: Focuses on Cheating people out of money and Revenge (and you cant forget, getting Hora back to her homeland.) They may contrast in background information, but they are both animes that you can relate to real life. For example, Spiral: There are detectives solving crimes today. Spiral gives you the feel of a classic Shurlock Holmes movie. For example, Spice and Wolf: Everyday, people are cheated out of money and everyone wants to get revenge on someone. I believe that these animes both focus on the skills and emotions of human beings. And to me, u can't have skills without emotions. So that is why I think that if you enjoyed Spiral you might like Spice and Wolf. read more 

Kaiji is constantly in situations of despair, but when it comes down to it he can create ridiculously amazing and effective strategies to break out from the seemingly impossible sitautions, similar to the latter parts of spiral where narumi is faced with problems with his life on the line. 

Both of these story lines deal with a high school student who has to solve puzzles in order to save people and the organizations that try to stop him.