The year is 2027, and the city of Kyoto has undergone tremendous technological advancement. Within the city live two classmates: Naomi Katagaki, a socially awkward and introverted boy; and Ruri Ichigyou, a girl with a cold personality who is often blunt with people. Despite sharing Ruri's love of reading, Naomi is afraid to approach her due to her unfriendly nature. One day, while out on a walk, Naomi witnesses a crimson aurora pierce through the sky for a brief moment before vanishing. Shortly after, he encounters a three-legged crow and a mysterious hooded man, who reveals himself to be Naomi from 10 years in the future, explaining that he has come to change an imminent tragic event that happens to Ruri soon after they start dating. Initially taking his words with a grain of salt, present-day Naomi follows his future self's instructions and starts getting closer to Ruri, determined to save her. Will he be able to change the future?

Entranced by surfing and the sea, Hinako Mukaimizu is a spirited girl who attends college in a coastal city with no consideration for her future career. Her life takes an unexpected turn when a fireworks mishap sets the apartment building she lives in ablaze, where she is saved by a talented firefighter named Minato Hinageshi. Upon meeting, the two quickly become acquainted with one another—Hinako is instantly enamored by Minato's reliable personality and passion for saving others, while Minato is intrigued by surfing and is eager to learn how. As Hinako begins to teach Minato about surfing, the pair eventually fall in love and begin a gentle and devoted relationship. However, while surfing may seem fun and carefree, it can still be a dangerous and unpredictable activity. This is what Hinako learns when a surfing incident completely changes her life, leaving her forced to contemplate her undecided future. In search of her own calling, Hinako begins her journey of self-discovery, keeping Minato by her side as she gradually attempts to find her purpose and ride her own wave.

With the tumultuous cultural festival behind him, Masamune Makabe continues his efforts to carry out his revenge: to make the "Cruel Princess" Aki Adagaki deeply fall for him and then immediately dump her. As his class is going on a trip to Paris, widely known as the City of Love, Masamune has the perfect opportunity to get even for his childhood heartbreak. Before Masamune can impress Aki, the two meet Muriel Besson, a French high school otaku who aspires to create a romantic comedy manga series. Muriel believes Masamune is the ideal model for the protagonist and asks for his help. The boy reluctantly agrees, dragging Aki along to provide inspiration for the love interest's character. But to do so, the two must show Muriel what Japanese love is like. To make matters more complicated, Kanetsugu Gasou is masquerading as Aki's childhood friend, Masamune, to trick and use her. With mix-ups and love rivals galore, Masamune's revenge is proving to be quite the difficult task.

Five years ago, gravity-defying bubbles with mysterious powers rained down upon the earth. After a huge explosion of uncertain origin, Tokyo became ground zero, with the city being enclosed in a gigantic bubble. As a result of this "Bubble Fall" phenomenon, the metropolis that was once the capital of Japan drowned in a gravity-bending sea; the government declared it a prohibited zone, and the residents abandoned it. Children orphaned by the Bubble Fall now squat illegally in Tokyo, partaking in dangerous parkour team battles across the city's dilapidated buildings. Hibiki—a talented ace in these games with the ability to jump between bubbles—claims he can hear sounds from the Tokyo Tower. Determined to uncover its mysteries, he sets off toward the source, but he falls into the waters below. A strange girl, whom he later nicknames Uta, saves him. But little does Hibiki know that Uta's appearance in his life will reveal the secrets behind the disastrous event that changed their world forever.