Out in the countryside stands a sweet shop run by the Shikada family for nine generations: Shikada Dagashi, a small business selling traditional Japanese candy. However, despite his father's pleas, Kokonotsu Shikada, an aspiring manga artist, adamantly refuses to inherit the family business. However, this may start to change with the arrival of the eccentric Hotaru Shidare. Hotaru is in search of Kokonotsu's father, with the goal of bringing him back to work for her family's company, Shidare Corporation, a world famous sweets manufacturer. Although the senior Shikada initially refuses, he states that he will change his mind on one condition: if Hotaru can convince Kokonotsu to take over the family shop. And so begins Hotaru's mission to enlighten the boy on the true joy of delicious and nostalgic dagashi!

In a futuristic society, Japan has implemented a complex system referred to as The Red Threads of Science to encourage successful marriages and combat increasingly low birthrates. Based on a compatibility calculation, young people at the age of 16 are assigned marriage partners by the government, with severe repercussions awaiting those who disobey the arrangement. For Yukari Nejima, a teen that considers himself average in every way, this system might be his best shot at living a fulfilling life. However, spurred by his infatuation for his classmate and long-time crush, Misaki Takasaki, Yukari defies the system and confesses his love. After some initial reluctance, Misaki reciprocates his feelings in a moment of passion. Unfortunately, before the two can further their relationship, Yukari receives his marriage notice. He is then thrown into a confusing web of love and lies when his less-than-thrilled assigned partner, Ririna Sanada, becomes fascinated with his illicit romance.

Fumiya Tomozaki is Japan's best player in the online game Attack Families, commonly known as Tackfam. Despite holding such a revered title, a lack of social skills and amiability causes him to fall short in his everyday high school life. Failing to have any friends, he blames the convoluted mechanics and unfair rules of life, forcing him to give up and proclaim himself a bottom-tier character in this game. After a fateful meeting with another top-tier Tackfam player, Fumiya is shocked to discover the player's true identity—Aoi Hinami, a popular, smart, and sociable classmate who is the complete opposite of himself. Aoi, surprised at how inept Fumiya is at everything besides Tackfam, decides to assist him in succeeding in what she calls the greatest game of them all. Through the gruesome ordeals of social interactions and relationships, Fumiya begins to advance tiers in the glorious game of life.

Now that Kumiko Oumae has enrolled in Kitauji High School, she hopes to forget about her past. Despite her desire for a fresh start, she gets dragged into the school's band club by her new friends—Sapphire Kawashima and Hazuki Katou—and is once again stuck playing the euphonium. As the band currently stands, they won't be able to participate in the local festival, Sunfest, let alone compete at a national level. The band's new advisor, Noboru Taki, gives them a choice: they can relax and have fun, or practice hard and attempt to get into nationals. Not wanting to repeat her mistakes from middle school, Kumiko is doubtful as to whether they should try for nationals. Amidst the chaos, she learns that her old bandmate, Reina Kousaka (who she had a bitter relationship with) has joined Kitauji's band club. Under the pressure of Noboru's strict training, Kumiko and her bandmates must learn to overcome their struggles and find success together.