In the seaside village of Hinashi Town, Kai Ashimoto's grandfather is one of the locals who reinforces the legend that mermaids lurk near Merfolk Island and consume humans. Due to allegedly attracting merfolk and subsequently causing the death of the elder's mother, music is seldom discussed in the Ashimoto household. Even so, Kai finds solace in making looped beats on his laptop and uploading them to the internet. Despite his reserved and glum demeanor, Kai is approached by Kunio and Yuuho Ebina, two cheerful classmates that happened upon one of his videos. The pair ask him to join their rock band but are met with apathy. Nevertheless, Kai agrees to accompany them in a practice session on Merfolk Island, where he soon witnesses something that he cannot explain. Later that night, Kai is composing music in his room when he attracts a familiar entity—a mermaid. As she twirls and grins to the sound of his stereo, Kai discovers a number of aspects about the being who introduces herself as Lu: she possesses incredible water manipulation powers; she buds a pair of functioning legs with the sound of music; but most notably, she is a truly benevolent creature who simply wants people to like her. Fostering a dynamic friendship, Kai and Lu gradually come to express their genuine selves, testing the long-standing boundaries that have deafened the resounding harmony among the people of Hinashi Town.

On a mysterious night that seems to last for a year, an ordinary college student continues to chase one of his underclassmen, a girl with black hair—the girl of his dreams. Up until now, he has been relying on a simple plan, which is to calculatingly bump into her every day while making it seem like a meaningful coincidence. However, his efforts remain futile as their relationship is not progressing at all. Meanwhile, the black-haired girl believes that everything is connected by fate and endeavors to experience as many new things as possible, leaving it all for destiny to decide. While strolling along the lively streets of Kyoto, she discovers that the very beginning of her fateful journey—a book she had as a child—is currently being sold in a second-hand bookstore. Upon knowing this, the college student eyes another opportunity to run into her by chance: this time, he hopes to get the book before she does and finally grasp the thread of fate that could connect their hearts.

One autumn evening at a mysterious ramen stand behind the Shimogamo Shrine, a lonely third-year college student bumps into a man with an eggplant-shaped head who calls himself a god of matrimony. Meeting this man causes the student to reflect upon his past two years at college—two years bitterly spent trying to break up couples on campus with his only friend Ozu, a ghoulish-looking man seemingly set on making his life as miserable as possible. Resolving to make the most out of the rest of his college life, the student attempts to ask out the unsociable but kind-hearted underclassman Akashi, yet fails to follow through, prompting him to regret not living out his college life differently. As soon as this thought passes through his head, however, he is hurtled through time and space to the beginning of his years at college and given another chance to live his life. Surreal, artistic, and mind-bending, Yojouhan Shinwa Taikei chronicles the misadventures of a young man on a journey to make friends, find love, and experience the rose-colored campus life he always dreamed of.

On a hot summer day in Kyoto, a young man walks toward his apartment, dreaming of turning on the air conditioner and cooling down. But before he can turn his dream into reality, disaster naturally strikes in the form of Ozu, who spills soda all over the remote. With the air conditioner rendered completely unusable, the man and his friends are left to suffer in the terrible August heat. Just when all hope seems lost, the group finds a true-to-life time machine in their storage room. Not knowing the dire consequences of doing so, they decide to travel back to the past and grab the remote before Ozu even has a chance to destroy it. What awaits them on the other side is a staggering adventure none of them are prepared for.