Veteran adventurer Nick, mage Tiana, cleric Zem, and half-dragon Curran each show up alone at a tavern, only to find themselves seated at the same table. As the night goes on, they take turns divulging their grievances and the hobbies they have taken up as a means of coping. While their stories are utterly different, there is one common thread: betrayal. Each of the four, having been bitterly betrayed by someone they treasured, has developed a deep-seated distrust of humanity. But in addition to their similar worldviews, the four have one more commonality: a critical lack of funds. Realizing that things cannot continue as they are, they decide to form a party, rank up, and make as much money as possible to spend on their respective hobbies. What these disillusioned adventurers do not know, however, is that they will one day save the world from unfathomable peril.

Wisteria is an orphan girl living in a corner of the British Empire at the end of the 19th century. Her life is desolate and bleak–until she encounters Marbas, a powerful but equally lonely immortal being with a furry appearance, hounded by hunters. Together, Wisteria and Marbas roam the Empire–populated by humans and human-like beasts–in search of a place where they can live together in peace.

The happy-go-lucky Michi Sonoda announces to her teammate, Sanae Takigawa, that she will quit judo for good after her final middle school tournament. This leaves Sanae in disbelief; after all, it was Michi's passion toward the sport that reeled Sanae into judo in the first place. Michi claims that a well-spent youth should be associated with things such as getting a boyfriend rather than sweaty tatami mats. However, Michi's plan to end her fledgling judo career with a bang is spoiled after experiencing an embarrassing defeat at the hands of the talented Towa Hiura. Later, her plan is further derailed when she finds out that Towa has enrolled in the same high school as herself and Sanae. With the sudden appearance of her past foe, Michi may soon realize that she still has lingering feelings for the sport of judo.

Kaname Okiura, a student of Prefectoral Umineko Shougyou High ("Umishou" for short), joined the school's swimming club in order to learn how to swim, but the club is filled with weirdos, let alone who can teach him swimming. Then, a sunny, happy-go-lucky girl named Amuro Ninagawa who transferred from Okinawa joined the club. Her extraordinary underwater speed and unorthodox swimming style (plus her personal habit of nude swimming—a powerful magnet to teenage boys) surprised every club member, especially Okiura, because she reminds him of a mermaid-like creature he saw only once in his early childhood.