Ren Fujii is a normal student who just had a fistfight with his former best friend, leading him to break off their friendship. But with the help of his childhood friend, Kasumi Ayase, and upperclassman, Rea Himuro, he's gradually returning to his normal school life. Then a series of brutal murders in which the victims are decapitated begins to strike their city. Strangely, at the same time, Ren starts to have terrifying nightmares of being beheaded by a guillotine. But these are just a prelude to the painful and terrifying battles to come. (Source: Crunchyroll)

One hundred boys, each of them in love with baseball, represent the Seidou High School baseball team. On any team, the Ace is the star of the game. Besides the main heroes, others are striving to attain this position, and each of them has their strengths, weaknesses, and emotional journeys that they have to undertake to become the best that they can be. Ryousuke Kominato is known in Seidou not only for his impressive fielding skills but also as an intimidating presence despite his small stature. While together with his partner, Youichi Kuramochi, they are the cornerstones of the team's defense on the field. Youichi is shadowed by his younger brother, Haruichi, whose admiration for Ryousuke is only matched by his own skills at the sport. Together with Yoichi's roommate, Eijun Sawamura, the players reminisce about their path to Seidou High.

Taichi Yagami and his friends have moved on to junior high, but by that time, they have lost contact with their Digimon partners. Taichi is therefore surprised to suddenly receive a distress call summoning him to the Digital World. Once there, he learns that Digimon are living in fear of the mysterious Digimon Emperor, who is somehow suppressing their ability to Digivolve! In the real world, Hikari Yagami and Takeru Takaishi reunite in the same fifth grade class. They share three schoolmates: Daisuke Motomiya, who reminds them both of Taichi; Miyako Inoue, a technical wizard; and Iori Hida, Miyako's neighbor. When these three children receive D-3 Digivices, they—along with Hikari and Takeru, who still possess their own original Digivices—comprise the new generation of Chosen Children who must save the world once again. With the power of the Armored Digi-Eggs, they must thwart the Digimon Emperor's plans to spread his influence over the entire Digital World.

The gate to the Digital World has been closed for three years. Taichi Yagami and his friends have since moved on, and now that he is in his second year of high school, it is time for him to grow up. While everyone else knows what they want to do with their lives, Taichi remains unsure. Meanwhile, the group drifts further apart as they follow their own paths. One day, a rogue insectoid Digimon called Kuwagamon materializes and disrupts electronics all over the city. Taichi recklessly chases after it and ends up cornered by the attacking Digimon. Suddenly, the Digivice that he still carries—a digital device that serves various purposes including helping one's Digimon partner to evolve—glows, and Agumon appears. The two are able to defeat Kuwagamon, but why did the Digimon cross over to this world in the first place? What is happening in the Digital World, and how exactly does this involve Meiko Mochizuki, the new transfer student in Taichi's class?