Set 23 years after the end of the original Future Card Buddyfight where the son of Gao Mikado, Yuga Mikado discovers Buddyfight for the first time. When he starts playing the game, he awakens his instincts and becomes an amazing buddyfighter over a short period of time. This attention brings along its own challenges from brand new rivals and friends. However, this fame and joy comes at a cost. This is the next generation of Buddyfight!

As the Holy Empire rises to power, the neighboring lands begin to gradually fall under its control. The Empire's conquest eventually reaches the small island of Erin, home to the Gael tribe. There, a priestess named Riannon is kidnapped to be offered as a living sacrifice to the demon king Arawn, a malevolent being rumored to have caused untold destruction in the past. Riannon's brother, First Warrior Arthur, rescues her, when Arawn suddenly materializes before them as a handsome grey-haired man. Hiding his true identity and remaining enigmatic, Arawn pledges his power and leadership to the tribe's cause and joins Arthur, Riannon, and their merry band of friends—including a talented swordsman, an agile hunter, and a group of ecstatic pixies—as they fight back against the Empire, while uncovering the dark secrets of the land along the way.

Buried within the numerous clubs at Nijigasaki High School lies the school idol club. The club, while lacking popularity, definitely does not lack potential. During their debut performance, they were able to seize a sizable audience, along with the attention of their schoolmates Ayumu Uehara and Yuu Takasaki. Enamored, the duo makes their way to join the club; however, they are disappointed to find out that the club had just been disbanded. Nevertheless, Ayumu does not believe that it should have ended there. Together with Yuu, they begin restoring the school idol club, hoping to recreate the idol performances that dazzled them before. Love Live! Nijigasaki Gakuen School Idol Doukoukai shines its spotlight over the reformed school idol club as they recruit both former members of the club alongside newcomers. Taking the first step towards their dreams, how will these girls achieve idol stardom?

Although cheerful and delicate, Sakura Sakurakouji is a skilled martial artist with a sense of fairness that never falters—no matter the situation. Upon witnessing people burning in blue flames while on a bus ride home, she calls the police to bring their murderer to justice only to find that no evidence remains. However, all her doubts about what she saw vanish when the next day, the new transfer student Rei Oogami joins her class; he is the very boy she watched commit murder in cold blood. Rei is kind, sweet, and quickly becomes popular, contradicting Sakura's accusations. Soon enough, she learns his true nature: a Code Breaker, or "one who does not exist." To Sakura's shock, Rei—armed with mysterious powers—seeks to exact justice according to the principle of "an eye for an eye." Determined to bring Rei to the right path, Sakura keeps close to him in the hopes of redeeming him from his ways before others are hurt.