Mari Kurihara is the President of the Underground Student Council at Hachimitsu Academy. Mari is unabashedly opposed to admitting boys into this, until recently, all-girls school. The one to approve this change, is the school chairman who happens to have a fetish for female posteriors, which he’s often seen admiring in photos or online, he also happens to be Mari’s father. Mari looks down on him because she often catches him looking at derrieres, which she finds disgusting. This disgust is the base for Mari’s hatred of men and for her plans to have the 5 male students expelled in an indirect attack towards the Chariman.

Mari and The Chairman come in at number 5 because of the passionate disdain Mari feels towards her father and how while trying to get the boys expelled, she also uses them as pawns in her power struggle with him. Not to be left behind, the Chairman takes every opportunity possible to give the boys a chance, not only because they’re his fellow men, but also because he wants his daughter to learn her lesson. The almost palpable, yet comedic, tension in the room when these two meet and the fact that the boys are used as game pieces makes this rivalry worth adding to the list!

Ibuki is designated as the heir to the Nil Kamui Throne by the Red Dragon, and is a “Child of Contract”. This contract gives him the ability to sacrifice a loved one’s soul in exchange for taking another’s life. However, Ibuki hates violence which puts him in a difficult position when defending his Kingdom. Ibuki’s younger sister Inori, is also an heir to the throne but is the complete opposite of her brother. Inori also has a contract with the Red Dragon, who’s madness she is revealed to be the cause of. Contrary to Ibuki’s, her power is that of revival. Innori is cold, and has completely opposite plans for the kingdom than Ibuki. When Ibuki realizes the sister he loves is a threat to the Kingdom, he is faced with having to fight her and perhaps even destroy her.

Sibling rivalry is perhaps one of the most classic types there are. At their young age, these two siblings are torn apart, manipulated, granted special powers and made to face each other with many lives and a Kingdom in the balance. The contrast between the siblings really adds more dimension to the rivalry since one of them, Inori, doesn’t really feel saddened by fighting her brother, while Ibuki is deeply pained by having to fight his beloved sister. Inori and Ibuki come in at number 3 because theirs gives an interesting spin to the time-honored sibling rivalry.

Kogoru Akechi, mostly known as Akechi in the series, is a young prodigious detective with success in all but one of the unique cases he has been involved with. That case being the 20 Faces case. 20 Faces is an unknown killer who murders criminals and other people who he/she believes deserve death. 20 Faces believes criminals get off too easily after committing crimes and that therefore somebody should give them what they deserve.

The criminal gives the police advance notice of the murders and taunts Akechi. Throughout the investigations 20 Faces even reveals that Akechi is a key to how and when the crimes will be committed. Akechi has not been able to catch 20 Faces in the years he’s been investigating the case. Akechi lost his best friend to 20 faces 3 years prior and this motivates him to, almost obsessively, work to solve the case.

Akechi and 20 Faces come in at number 3 because of the degree of obsession with which both Akechi and 20 Faces approach each other. It’s almost reminiscent of Light Yagami and L in Death Note. Not to mention, there are people’s lives on the line. It’s a dark twist on the typical genius detective vs evil mastermind rivalry that could only come from basing this series on Rampo Edogawa’s Mystery Fiction novels.

Masamune Matsuoka is a member of the survival team Toy☆GunGun. He is very skilled, charismatic and strives to always have fun. Nagamasa Midori was once a teammate of Matsuoka before, for reasons unknown, deciding to split from him. Midori is a bit two-faced and can switch from being a gentle doctor to a bit of a sadist towards his teammates and opponents on the field during survival games. Midori enjoys emotionally torturing Matsuoka and due to an occurrence involving someone special to him in the past, Matsuoka has become obsessed with beating Midori at TGC (a secret survival game tournament). Midori’s past and present bullying causes Matsuoka to stand in shock and almost cry when he runs into him for the first time in a year.

Matsuoka and Midori come in second place because of the sheer intensity with which these characters react to each other. Midori doesn’t care who he tortures to in order to humiliate Matsuoka, and even the usually kindhearted Matsuoka, though left trembling when faced with Midori, loses sight of his friends in his blind pursuit of vengeance against Midori.

Midori is the monster we love to hate, while the audience really feels for Matsuoka and roots for him to get his revenge. These are two rivals who illicit so much emotion in each other and the spectator that we can’t help but watch what happens next.

Nagisa Kiryuu is a newly transferred third year high school student and third son of the Kiryuu family who run the space aeronautics mega corporation Kirishina Corp. Yuuji is the second brother and is senior managing director. After being sent all over the solar system and having successfully dealt with all tasks appointed to him, Nagisa is transferred to the Mars branch and ordered by Yuuji to disband A-TEC, an advanced technological education class of which he is also a student.

Nagisa has been succeeding at every seemingly impossible task thrown at him by the Kirishina Corporation because he wishes to overthrow his two brothers as part of a personal vendetta. As his immediate supervisor and boss, Yuuji verbally and sometimes physically abuses Nagisa repeatedly, which only spurs Nagisa on in fighting to take him down. Nagisa even attempts manipulating politics in order to get his way, which eventually brings Yuuji to put a hit on Nagisa.

This life-long rivalry makes it at number 1 because there is so much passion between the rivals. Yuuji hates Nagisa so much and wants him out of his life and the corporation badly enough that he treats him like trash and has him kidnapped, beaten and almost killed. All the while Nagisa endures being sent out expected to fail and faces certain death several times, only to get revenge on his terrible brother Yuuji and the rest of the Kiryuu family. He will sacrifice anything to fulfill his vengeful wishes. With lives, corporations and people’s sanity on the line, this is definitely a memorable rivalry which we’ll hopefully get to see more of.