Koushi Inuzuka is a smart high school student who aims to become a public prosecutor. Unfortunately for our good guy, he was born into a martial arts family whose head (ie his father) only knows one language: violence. When Koushi was still a baby, his father made a pact with his biggest rival to marry Koushi to his opponent-turned-friend's daughter. The union of the two blood lines is supposed to bring forth Earth's strongest martial arts clan.
Skip forward: Koushi is in high school, oblivious to the marriage arranged for him at his birth. Enter Momoko Kuzuryuu: sugar bomb, airhead, loli martial arts artist and Koushi's self-proclaimed bride (the strongest on Earth, no less). Her wish for sexual intercourse meets with Koushi's square refusal as he has absolutely no desire to get it on with someone who looks like she could be his little sister, not to mention that he doesn't have the foggiest idea who she actually is.
Meanwhile, a war has broken out between the martial arts families. For Koushi, this means that numerous fighters are out to challenge/assassinate him. As if that weren't bad enough, our protagonist also has a fight phobia due to a traumatic incident that took place in his childhood. Now it's up to Momoko and her superhuman fighting skills to protect her "husband." Will the two sweethearts survive the trials and tribulations ahead of them? More importantly, will Momoko get her way receiving a baby from Koushi?
(Source: Kotonoha)
Momoko joins Kōshi's class, much to his surprise. The gym leader, jealous of Kōshi's popularity with a lot of the female students, challenges Momoko to athletic contests with Kōshi's credit in the class on the line.
Kōshi and Momoko go to the zoo together, though before long, animals escape their cages and a massive polar bear attacks them. All of this is a plot by Iroha to kill Kōshi.
Iroha tries once again to kill Kōshi but gets caught up in the moment when Kōshi and Momoko are showing her around the park. Eventually, Hanzō has to step in to try to complete the mission.
After learning about the meaning between their marriage from his father, Kōshi starts to act nicer towards Momoko though soon worries about being manipulated and distances himself from her. Eventually, Kōshi realizes how much he has hurt her and tries to rectify for his actions.
Iroha and Hanzō join Kōshi's school and instantly Iroha notices how friendly he and Sanae are to each other. Iroha proceeds to help Momoko convey her feelings more strongly to Kōshi.
Sanae, as a member of the Horse family of the zodiac Masters, is bound to protect Kōshi from danger without revealing herself to anyone. She is constantly battling the feelings she has for him.
Sanae's fiancé tries to prove to her through various strength tests to show her that he is worthy of becoming her husband. Meanwhile, Sanae is having enough trouble just keeping her martial arts background a secret from Kōshi.
Both Kōshi and Hanzō come down with a cold, though Hanzō is almost completely ignored by Iroha in favor of Kōshi. Hanzō gets very jealous of Kōshi and starts tormenting him by impersonating him and others in order to harm Kōshi.
A new female teacher has been hired at Kōshi's school who is very well-endowed and knowledgeable about the law. Before long, Sanae begins to suspect her of being an assassin and attempts to confirm her suspicions.
A girl, thought to be dead due to an accident at the school's cultural festival decades previous, has resurfaced. It is rumored that she died before she got a chance to confess her love to Kōshi's father. Kōshi hence agrees to date the girl so that she can peacefully rest in heaven.
Saigō meets the girl of his dreams after he thought he protected her from thugs. The girl is actually a martial artist coming from a tribe known for training assassins. The girl is given a choice: Kill Kōshi, or Saigō will be killed.
Momoko gets some advice from a television program about how to make Kōshi notice her more, but her initial attempts fail. Iroha and Hanzō try to help out as well, but with no much success. At the end of the episode, Momoko and Kōshi find a disheveled Tenka.
Tenka is taken back to Kōshi's house where he is given nourishment. He informs Kōshi and Momoko that his siblings are coming to kill Kōshi. Tenka's younger brother arrives to try to assassinate Kōshi, and Tenka attempts to stop him.
Kōshi's house has burned down and he must now move into the same apartment building as Iroha and Hanzō; Tenka lives there too. As a welcoming party, the landlady hosts a special welcoming party involving nabemono.
A woman claiming to have been fired from being employed as a maid arrives at the apartment building. where Kōshi is currently staying. She initially comes off as a kind and helpful person but soon reveals to Momoko that she is an assassin who has come to kill Kōshi. Momoko tries to plead her case to the others, but no one will believe her.
Kōshi was made to swallow a ball of poison from the Tenga clan and was told that in a week he will die unless he is given an antidote. Momoko willingly swallows the same poison so that if Kōshi dies, she does as well. Momoko and the other martial artists on their side train for a week, and Kōshi tries to learn a technique of his own, but fails. Kōshi and the others then go to the Tenga clan's main house and must fight several battles to gain the antidote.
