Yō Satō finds himself beaten up on the supermarket floor, the last thing he remembers being going to get some half-priced bento. The next day, he encounters a silver haired girl who warns him not to go to the store again. He goes again alongside another student, Hana Oshiroi, and finds himself beaten up again upon reaching for the half price bento. The next day, he decides to act more strategically and witnesses an all-out battle for the bento that gets marked half-price, which is dominated by the silver haired girl, Sen Yarizui. After the battle ends in total defeat for Yō, Sen tells him to come to the Half-Priced Food Lovers club

Sen gets Yō and Hana to join the Half-Priced Food Lovers Club and starts training them in the ways of Bento Brawling. During one of the supermarket visits, they encounter a 'boar', a fat woman who raids all the half-priced bentos before a battle starts. The next day, Yō meets Yuu 'Wizard' Kaneshiro, who encourages Yō to stand up to a boar so that the bento battle can properly take place. Yō comes to understand the pride of the 'wolves' and comes out with his first victory, obtaining a bento with an honor seal from the 'God of Discounts'. Yō then returns to the clubroom, where Sen congratulates him on his first victory and shows him a scrapbook showing the victories Yuu managed to obtain.

Yo gets a lot of hassle from the class president, Ume Shiraume, due to him hanging around Hana. As Yo and Hana go to a supermarket, they meet a kendo club member named Yamahara, who invites them to join a group called the Hounds, who use teamwork to help members get half-priced bento. As Yo and Hana take a trial period with the group, Yo feels the bento he obtains this method don't taste as good as he thinks. After reminiscing about old times, Yo turns down Yamahara's offer, realising that food tastes best when you fight for it. Having realised the true meaning of half-price bento, Sen gives Yo and Hana keys to the club room. The next morning, Yo finds his childhood friend, Ayame Shaga, sleeping in his bed.

Ayame is revealed to be a wolf known as 'The Beauty of the Lake' who throws down a challenge to Sen. After barely escaping from the wrath of Ume, Ayame accompanies Yo and Sen to a bento brawl, where she and Sen fight for the same bento. As Sen manages to defeat Ayame and claim her bento, Yo finds himself against a tough opponent but manages to win in the end.

Yo goes through some hassle to meet up with Ayame, where he also meets Asebi Inoue, who gives bad luck to anyone she touches. As Yo goes to a store with the others, he finds himself up against Ren Nikaidō, who is part of a group known as Gabriel Ratchett, and gets severely beaten by someone known as 'Monarch'. After Yo regains consciousness, Ayame explains how the Monarch seeks revenge for some ancient slight, while Sen questions why she didn't warn Yu about him.

As Sen heads towards a store alone, Ayame learns about how Yū triumphed over the previous Monarch Butterfly, Matsuba, with Endo, her successor, wanting revenge on Yū's successor, Sen. As Ayame warns Yō about this, Sen, who had gotten severely beaten up by the Gabriel Retchetts, arrives at the Ralph Store to face against Endo. As Ren feels regret after hearing words of disappointment from Matsuba, the current God of Discounts, he tries to stop Endo but is knocked away. As the brawl begins, Yō and Ayame arrive and together they manage to defeat Endo. Afterwards, Ren follows Matsuba's advice and starts to live for himself. Meanwhile, Yū leaves the country to study overseas.

Matsuba gives Yo, Sen, Ayame and Hana free tickets to an indoor swimming pool, where they also run into Ren. There, they discover even a swimming pool has half-priced bento, featuring a unique bento brawl across the pool. As the waves provide a feirce battlefield, Yo manages to achieve his prey, albeit not without an embarrassing comeuppance.

Yo becomes hospitalised after jumping out of a window whilst trying to protect his Sega Saturn that Sen threw out the window, ending up completely wrapped in bandages. Meanwhile, a pair of twin sisters from Ayame's school both named Kyo Sawagi, the older of which appears to have a thing for Sen, infiltrate the hospital hoping to meet Sen. They mistake Yo for Sen and perform some curious inspections on him, leading to chaos when they actually learn the truth.

Asebi decides to make Yo a homemade bento, where everything component tastes of something completely different. Meanwhile, Ume meets up with the Sawagi sisters concerning both Yo and Ayame trespassing on each other's schools. Later that night, as Hana has an accident with her computer whilst finishing up one of her erotic novels, Ume believes her to have fallen sick and comes over to tend to her 'fever'. As she does, she discovers one of Hana's books which she had posted Yo's face all over. As Ume goes to punish Yo for this, Yo reveals Hana's passion for writing gay fiction, but she does not believe him and beats him to a pulp.

... and Dried Sardines over Rice with Plenty of Stewed Seasonal Vegetables Bento 480kcal Ayame is visited by Ren who tells her about a group called Orthros who are severely attacking other wolves and placing baskets on their heads. As Yo resumes his bento brawl duties, he becomes the latest victim to the Sawagi sisters. As Yo, Sen, Ayame and the others get together at a supermarket for a bento brawl the next day, Sen soon finds herself attacked by the sisters and, despite assistance from the others, is severely beaten.

Yo goes to visit Sen, who had been absent from school with a cold, where she discusses plans to fight against the twins for eel bentos in a few days. After another defeat by the twins, Yo and Ren learn from Ayame that they are the daughters of a chain store owner who came over from Yumehiro. Ren travels to Yumehiro to find out more while Ayame passes on Sen's message to the twins, although Sen's cold has gotten worse. Ren learns that, three years ago, the twins were driven out of Yumehiro by a brawler known as The Club of Hercules.

With four hours left until the bento brawl and Sen still not over her fever, Yo decides to let her sleep in whilst he goes in her stead. On the way he encounters Hercules, who tells him something that causes him to run away. As the twins arrive at the store, they encounter Hercules, who is forcing the cooperation of the other wolves to exclude them from the fight, just like he did three years ago. However, Yo returns, having ran to build up an appetite which reminds the other wolves why they fight and convinces them to brawl fairly. After beating Hercules, Yo manages to convince the twins to join in the fight, where the twins are defeated and Yo wins the prize seal to share with Sen.