Fudou Aikawa and Desumi Magahara have just started dating, but no one is allowed to know! Nicknamed "Red Gelato," Fudou is the leader of "Gelato 5," a group of heroes dedicated to protecting Japan. On the other hand, the "Reaper Princess" Desumi is one of the combatant leaders of "Gekko," an evil secret society bent on world domination and considered Gelato 5's greatest foe. As they pretend to be mortal enemies, Fudou and Desumi sneak away from battle to spend time together. Despite their inexperience with romance, Fudou and Desumi strive to make their relationship work while avoiding suspicion from their comrades. With their loyalties divided between each other and their respective sides, the couple will have to stay on guard if they want to keep their love a secret from the rest of the world.

Listless geek Mizuto Irido and introverted nerd Yume Ayai seemed like a match made in heaven, connected by their mutual love for literature. Unfortunately, their differences gradually grew, and they separated just after their middle school graduation. But, as if by divine comedy, the two find themselves reunited as step-siblings. A rivalry begins to brew between the former couple, both unwilling to acknowledge the other as the older sibling. In an attempt to "solve" this issue, Mizuto and Yume agree upon a rule: whoever crosses the boundaries of siblinghood norms loses, and the winner will not only be called the older sibling, but also get to make a request. However, now that they live under the same roof, the lingering memories they share start to influence their actions—possibly rekindling the feelings that may not have been fully extinguished in the first place.

Former ace runner of Sendai Josei High School, Kakeru Kurahara is chased away from a convenience store for shoplifting. Shaking off his pursuer, he runs into Haiji Kiyose, another student from his university. Haiji is impressed by Kakeru's agility and persuades him to live in Chikusei-sou, the run-down apartment where Haiji resides along with eight other students. Having lost his entire apartment deposit at a mahjong parlor, Kakeru accepts the offer reluctantly. However, Haiji reveals a secret during Kakeru's welcoming party: the apartment is actually the dormitory of the Kansei University Track Club. He unveils his ultimate goal of participating in the Hakone Ekiden—one of the most prominent university marathon relay races in Japan. Unfortunately, all the residents apart from Haiji and Kakeru are complete running novices. Worse still, none of the inhabitants are even remotely interested in being involved with Haiji's ridiculous plan! With only months before the deadline, will the fourth-year student be able to convince them otherwise and realize his elusive dream of running in the Hakone Ekiden?

In the ancient Shakya Kingdom, King Suddhodhana learns that his wife, Maya, has a curious dream. A white elephant with six tusks enters her body—a sign that their future child, Siddhartha Gautama, is blessed. The wise prophet Master Asita sees the child and foretells that he will become "chakravartin," the ruler of the world. Meanwhile, young Chapra suffers the injustice of the rigid caste system. When Kosala army marches on Kapilavastu, Shakya's capital, Chapra plays a part in forcing them to retreat. But to escape the life of slavery and give his mother a better life, Chapra joins the Kosala army and swears to rise in the ranks. As the young Siddhartha grows, he is taught everything he needs to know to inherit the throne. However, Siddhartha has no interest in martial arts or running a kingdom. What he seeks are the truths of the world and the meaning of life itself. Although Kosala's ever-expanding power threatens Shakya, Siddhartha abandons the royal life and ventures into the world to find the enlightenment he desires.