After inheriting the company from their parents, siblings Yuuhi and Yuamu Oudou have started to work at Ultraterrestrial Trouble Solutions, an organization that hunts aliens. Although they have never encountered aliens before, Yuuhi is desperate to meet one as he believes that an alien has stolen his important item called the "Earthdamar." One day, while searching for extraterrestrial creatures, Yuuhi and Yuamu find a strange spot in the forest where many trees have fallen, forming a scenery similar to a crop circle. As they venture further, they discover a mysterious spaceship and enter it out of curiosity. To their surprise, they come across Yudias Velgear, an alien from the Velgear Star Cluster. As it turns out, Yudias is seeking to learn about Rush Duel—a card game popular among elementary school students—as he believes that it will save his home from a long war. With the siblings agreeing to teach Yudias about Rush Duel, they eventually realize that their first contact with an alien may not be a random coincidence.

General of the Three Kingdoms, Kongming had struggled his whole life, facing countless battles that made him into the accomplished strategist he was. So on his deathbed, he wished only to be reborn into a peaceful world... and was sent straight to modern-day party-central, Tokyo! Can even a brilliant strategist like Kongming adapt to the wild beats and even wilder party people?!

Yuuichi Katagiri has battled financial hardships his whole life but has learned to stay content and positive thanks to his close circle of friends. To keep a promise he made to them, Yuuichi saves up enough money to join them on the school trip. But when the gathered money mysteriously goes missing, suspicion falls on two of Yuuichi's friends: Shiho Sawaragi and Makoto Shibe, who were in charge of collecting the payments. Although innocent, Shiho and Makoto take responsibility for the failure to protect the money when no one else comes forward. A few days later, Yuuichi and his friends receive mysterious letters which trick each of them into meeting up. Upon arrival, they are ambushed and knocked unconscious. They wake up in a mysterious room in the presence of "Manabu-kun," a character from a controversial children's show that stopped airing due to its malicious content. He informs the group that one of them indirectly gathered them together in order to settle a large debt. They are to play a "friendship game": a series of games that will test the strength of their bond and trust in each other. As the group's faith wavers due to the growing number of secrets and betrayals, Yuuichi must figure out who of his "friends" he can actually trust and ultimately discover the identity of the traitor.