The Rift between the present world and the another world caused by the instability of energy is the only passage to the present world for the monsters in another world. In order to block the invasion of monsters, in the present world, a group of people with special power bravely stand in the Rift to defend the world.

Murai is a second-year student at Takebe Gakuen High School enrolled in the college preparatory course. His homeroom teacher, Tanaka, summons him to her office after he declares that his post-high school plans are to marry her. Tanaka rejects Murai, telling him that she would never be interested in a boy with long, black hair. Secretly an otaku, she has eyes only for Hitotose, a character from an otome video game. The next day, Murai appears before Tanaka a changed man. Having cut his hair short and dyed it blond, Murai looks exactly like her beloved Hitotose. Tanaka is unable to hide her shock at this sudden development and tries to distance herself from Murai, while Murai presses on in his attempts to romance his teacher.

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.

Kio is just another boring, nice guy with a boring, nice life until he meets a beautiful, curvaceous cat-girl while attending a memorial service for one of his ancestors. Next thing he knows, he's lying in bed with this half-naked beauty next to him! Her name is Eris, and she has come to Earth to learn more about its inhabitants as a representative of the planet Catian. And she's decided to set up shop at Kio's home for her stay on Earth! Unbeknownst to Kio, there are quite a few organizations who will attempt to capture Eris, looking to keep her existence a secret by any means necessary. What's worse is when people around Kio turn out to secretly be a part of those organizations! Kio will have to work hard to keep Eris safe from these shady groups. Things are about to get mysterious, exciting, and most importantly sexy in Asobi ni Iku yo!