Through their tutor Fuutarou Uesugi's diligent guidance, the Nakano quintuplets' academic performance shows signs of improvement, even if their path to graduation is still rocky. However, as they continue to cause various situations that delay any actual tutoring, Fuutarou becomes increasingly involved with their personal lives, further complicating their relationship with each other. On another note, Fuutarou slowly begins to realize the existence of a possible connection between him and the past he believes to have shared with one of the five girls. With everyone's feelings beginning to develop and overlap, will they be able to keep their bond strictly to that of a teacher and his students—or will it mature into something else entirely?

Hitohito Tadano is an ordinary boy who heads into his first day of high school with a clear plan: to avoid trouble and do his best to blend in with others. Unfortunately, he fails right away when he takes the seat beside the school's madonna—Shouko Komi. His peers now recognize him as someone to eliminate for a chance to sit next to the most beautiful girl in class. Gorgeous and graceful with long, dark hair, Komi is universally adored and immensely popular despite her mysterious persona. However, unbeknownst to everyone, she has crippling anxiety and a communication disorder which prevents her from wholeheartedly socializing with her classmates. When left alone in the classroom, a chain of events forces Komi to interact with Tadano through writing on the blackboard, as if in a one-way conversation. Being the first person to realize she cannot communicate properly, Tadano picks up the chalk and begins to write as well. He eventually discovers that Komi's goal is to make one hundred friends during her time in high school. To this end, he decides to lend her a helping hand, thus also becoming her first-ever friend.

Eighteen-year-old Tsukasa Mizugaki has failed his college entrance exams, but after pulling some strings, he manages to land a job at the Sion Artificial Intelligence Corporation. SAI Corp is responsible for the creation of Giftias—highly advanced androids which are almost indiscernible from normal humans. However, unlike humans, Giftias have a maximum lifespan of 81,920 hours, or around nine years and four months. Terminal Service One, the station Tsukasa was assigned to, is responsible for collecting Giftias that have met their expiration date, before they lose their memories and become hostile. Promptly after joining Terminal Service One, Tsukasa is partnered with a beautiful Giftia named Isla. She is a Terminal Service veteran and considered the best in Giftia retrievals, contrary to her petite figure and placid nature. Time is fleeting though, and Tsukasa must come to terms with his feelings for Isla before her time is up. No matter how much someone desires it, nothing lasts forever.

In ancient Disboard, Riku is an angry, young warrior intent on saving humanity from the warring Exceed, the 16 sentient species, fighting to establish the One True God among the Old Deus. In a lawless land, humanity's lack of magic and weak bodies have made them easy targets for the other Exceed, leaving the humans on the brink of extinction. One day, however, hope returns to humanity when Riku finds a powerful female Ex-Machina, whom he names Schwi, in an abandoned elf city. Exiled from her Cluster because of her research into human emotions, Schwi is convinced that humanity has only survived due to the power of these feelings and is determined to understand the human heart. Forming an unlikely partnership in the midst of the overwhelming chaos, Riku and Schwi must now find the answers to their individual shortcomings in each other, and discover for themselves what it truly means to be human as they fight for their lives together against all odds. Each with a powerful new ally in tow, it is now up to them to prevent the extinction of the human race and establish peace throughout Disboard.