When Nashiko Jippensha's mother kicks her out of the house for being too loud, the high school girl needs to find a new place to hang out with her friends. Luckily, Nashiko's father owns a closed-down mahjong parlor that is perfect for her needs. While cleaning out the place, Nashiko discovers a talking bird who introduces himself as a mahjong spirit, encouraging her to try playing the game with her friends. Realizing that they enjoy the game immensely, Nashiko and her friends decide to continue playing and enjoy the new space they have to hang out.

With Rabbi Village greatly expanding under the management of his subordinates Isami Tahara and Yuu Kirino, Hakuto Kunai can now resume his adventures while looking for items to counteract magic. He begins his search at the Prison Labyrinth in Rookie Town, where a secret laboratory deep within the dungeon gives him insight into technology that is far more advanced and dangerous than anything in the rest of the world. Meanwhile, Rabbi Village has gained unwanted international attention from the newly formed Queendom of Xenobia, which wishes to drive a wedge between the Holy Kingdom of Light and the State of Right. But with Kunai's newly summoned aide, Akane Fujisaki, at his disposal, things may not go as the Queendom plans.

As technology advanced, humanity gradually colonized the entire solar system, occupying planetary facilities from Mercury to Pluto. This results in a large-scale athletic tournament, the Daiundoukai, where several aspiring female athletes from all around the solar system compete. The winner of the tournament is crowned the Cosmo Beauty, obtaining a queenlike status. When outgoing potato farmer Kanata Akehoshi was a child, she witnessed a meteor-like object falling from the sky, crashing in a nearby forest. When she came to investigate the wreckage, she saw a damaged spaceship and a girl who seemed to have been in it weakened by the impact. The girl gave Kanata two wristbands, alongside a request that Kanata join the Daiundoukai and become the Cosmo Beauty. Kanata obliged, but before she could ask for the girl's name, she mysteriously disappeared—leaving nothing,not even the crater caused by the crash. Since then, Kanata has devoted herself to training, aiming to fulfill her promise. After winning the qualifying round to represent the planet Earth, Kanata goes to the University Satellite—an institution where she and other candidates study to prepare themselves for the upcoming competition. There, she meets and befriends her fellow competitors, helping them get along with each other to perform better in the games. As Kanata grows closer to the coveted title, so do her chances of meeting the girl who changed her fate—and she discovers an underlying mystery behind the Daiundoukai along the way.

Following the events of their trip to Okinawa, Saitama University graduate students Shinya Yukimura and Ayame Himuro have failed to obtain the data necessary to scientifically prove their love for each other. Unable to replicate the exact conditions of the trip, the two stubborn scientists decide to seek help from elsewhere in the university—the Biological Sciences department. Assisted by fellow graduate students and longtime couple Chris Floret and Suiu Fujiwara, Yukimura and Himuro begin to quantify their feelings by measuring their output of oxytocin in various romantic situations. The two scientists soon find that their feelings for each other are nothing compared to that of a mature couple. It is here that Chris poses a question to both Yukimura and Himuro: what will they do if their affection is proven not to be love after all? Desperate to find a scientific rationale for the discrepancy, Yukimura puts everything on the line to prove that their love is real.