The Big Four, also known as the Four Heavenly Empresses of Martial Arts or 4 Devas(四天王) is the name of the group who are recognized as the four strongest people in the world.
The Big Four are not allowed to lose a fight with a person outside of the group, but they can fight between themselves to determined who is the strongest member without losing their status as member of the Big Four.
If a member loses a fight to a challenger, they are replaced in the Big Four by the person who beat them, the new member wins the title of the defeated member, along the position the former member have in the group. This means that if the challenger takes the position of a new member of the Big Four, they are automatically known as the previous rank of the former Big Four member. For example: if Ageha was ever defeated (which has not happened thus far), her title as second will be passed down to the person who beat her, without the person beating the third and fourth.
KAWAKAMI MOMOYO OF THE NORTHEditKawakami Momoyo is the strongest member of the Big Four. She defeated Kuki Ageha of the South in 2008 and won the position of the strongest between the Big Four. At an undisclosed point in time, she also defeated Tachibana Takae of the west.
As of 2009, she has yet to face two members of the group, Kurogane Otome and Mayuzumi Yukie.
KUKI AGEHA OF THE SOUTHEdit
Ageha is the second strongest member of the Big Four, she lost the battle with Momoyo to determined who was the strongest between the Big Four.
She defeated Kurogane Otome of the East and Tachibana Takae of the West to win her position in the Big Four.
It also important to note that Kuki Ageha, while still being one of The Big Four, has stated that she's no longer trying her best as a warrior because she has to manage family's businesses.
Kurogane Otome of the EastEdit
Kurogane Otome of the East is the third member of the big four In 'Maji De Watashi Ni Koi Shinasai' and is a the main heroine from the 'Tsyokiss' series which, along with 'Kimi ga Aruji de Shitsuji Ore de' series, takes place in the same Japan, world, timeline and enviroment as 'Maji De Watashi Ni Koi Shinasai' (With the events from both happening at an earlier time before the year 2009 when the 'Maji De Watashi Ni Koi Shinasai' storyline starts) She is the third strongest member and is featured in a battle in the Kawakami war were she, Yukie and Ageha teamed up against Momoyo. During the fight, she is the only one not to be defeated, but only due to Momoyo not being able to engage her before the Kawakami war was won.
In The Visual Novel her name is only seen in the narration but is never said out loud by anyone and she is never seen due to not having a character image. She is still noticable from her voice.
In The 'Maji De Watashi Ni Koi Shinasai S' timelime she is not featured, but it is mentioned that she retires from fighting in order to be a teacher.In the Manga adaption, she goes by the disguise of "Iron Lady of Justice" due to "Circumstances", stating that in the adult world, there are things that being a martial artists can't fix. She dons her old martial arts uniform whilst concealing her face.
MATSUNAGA TSUBAME OF THE EASTEdit
Tsubame is the newest member of the Big Four in Maji De Watashi ni Koi Shinasai S. She defeated Kurogane Otome (Kan Otome in the VN.) of the East before she transferred to Kawakami Academy sometime after the events of the original Maji De Watashi ni Koi Shinasai .
During her route, she defeats Momoyo Kawakami in an exhibition match after winning the Tag Tournament. After seeing this along with her defeating other top tier fighters, Tesshin Kawakami, Nabeshima, Gyobu Shakadou and Hyumu Hellsing officially make her a member of the Big Four.
Although she hasn't defended her position against Yukie, who like her is a new member in the Big Four, she has victories against Momoyo and Seiso Hazakura with preparation. However, she has been defeated by Ageha Kuki and has admitted that Momoyo is stronger than her, so her level in strength amongst the group has yet to be determined.
MAYUZUMI YUKIE OF THE WESTEdit
Yukie is one the new member of the Big Four after she defeated Tachibana Takae of the West before she transfered to Kawakami Academy.
She defeated the weakest member of the Big Four, but is not recognized as the weakest due to not facing any other members of the Big Four.
There is currently one confirmed ex-member of the Big Four in all adaptions of Maji de Watashi ni Koi Shinasai.
Takae Tachibana of the West was the weakest member, but was also known to be the fastest amongst them. She was defeated by Mayuzumi Yukie, losing her position and title in the Big Four. Takae is the main antagonist in anime adaption. After retiring from The Big Four, she worked as a member of the JSDF, but was betrayed by her surperiors when she was attacked by refugees, which caused her to lose her limbs. She was taken in by the Kuki Corporation and given cybernetic limbs, but she escaped, vowing vengeance against those who betrayed her, one of which was the current Prime Minister of Japan. Her objective was supposedly to wreak chaos in Japan with the help of her subordinate, Saki Mimori, hiring the Itagaki Siblings and Shakadou Gyobu as her support. But she reveals that her true goal was to make sure that the soldiers of Japan would be treated better than she was treated by high level officials, even if it meant dying in the process. After being defeated by Momoyo, she is taken in by the Kuki Corporation by Ageha Kuki.
In the Visual Novel, Takae lives alone due to having an aura that emits bad luck. This is shown in the various routes she appears in, including her side route in Majikoi S. The Big Four do meet with her from time to time to check up on her.