Finally, the day of Mai's high school graduation has arrived. While Sakuta eagerly waits for his girlfriend, an elementary schooler who looks exactly like her appears before him. Suspicious, and for all the wrong reasons... Meanwhile, Sakuta and Kaede's father suddenly calls, saying that their mother wants to see her daughter. She was hospitalized because Kaede's condition had been too much for her to bear, so what could she possibly want now?

After a draining December, Sakuta is quickly nearing the end of his second year of high school. Since Mai is a third-year student, they don't have much time left together before graduation rolls around. Meanwhile, his sister, Kaede, is slowly but steadily venturing outdoors again. Just as she begins to find her footing, she announces her most ambitious goal yet—attending her brother's high school! Sakuta knows better than anyone how difficult this will be for Kaede, and he's ready to support her however he can. He's just not sure if that's what's best for her...or what she really wants...

In Eternal Nations, a fantasy strategy game where players manage an empire, Takuto Ira is a legendary player who sits atop the leaderboard. Takuto goes unconscious during a hospitalization and awakens on the continent of Idoragya, which looks just like the game. Takuto meets Sludge Atou, his favorite unit in the game, and decides to build Mynoghra, an evil empire.

Akira Kiyose, a high schooler who loves to sing, gets recruited by a talent agency called sMiLea Production. Akira learns that the legendary idols “Anela”, who shocked the world with their sudden retirement, are behind the agency developing talent. Together with Banri Naoe and Chihiro Isuzugawa, also recruited by the agency, they form an idol group as they chase their dream towards super stardom alongside other idol groups “LEGIT” and “JAXX/JAXX”.

In Big Money City, players participate in "Hero Battles" using Bankfon Gs, which allows them to rent powerful hero suits and fight battles against other players, receiving power boosts from the system's public domain feature. Kaito Goushou, a young elementary school student who is always eager to help others, ends up hastily signing a contract to rent the powerful unlisted hero suit, "Enter the Gold," from a mysteriously seedy priest named Sennen; however, he soon learns that the suit comes with a debt of 10 billion yen, and Kaito must now clear his dues by winning Hero Battles.