One fateful day, Youtarou Misaki is rescued by a man named Arashi Mutou from drowning in the sea. After getting him to dry land, Arashi wakes Youtarou up and asks for his name. Youtarou's memories quickly surge back, but instead of telling Arashi his name, he decides to lie and act clueless about his past. Arashi nurses Youtarou and lets him temporarily stay at his diner, Kurage no Shokudou. Despite his hospitality, Youtarou continues to insist that he has no recollection of how he ended up drifting across the sea. How will the fake amnesiac go on with his life now that he has abandoned his family and home?

In a world covered by an endless sea of sand, there sails an island known as the Mud Whale. In its interior lies an ancient town, where the majority of its inhabitants are said to be Marked, a double-edged trait that grants them supernatural abilities at the cost of an untimely death. Chakuro is the village archivist; young and curious, he spends his time documenting the discovery of newfound islands. But each one is like the rest—abandoned save for the remnants of those who lived there long ago. For the first time in six months, another island crosses the horizon, so Chakuro and his friends join the scouting group. During the expedition, they find vestiges of an archaic civilization. And inside one of its crumbling remains, Chakuro discovers a girl who will change his destiny and the world inside the Mud Whale as he knows it.

Special episodes included in the Blu-ray and DVD boxes of Kuma Miko.

After fanatically playing the VRMMO World Fantasy Online for almost a year, the shut-in yet relatively affluent 15-year-old Yuna receives a bear costume from the game's administrators. The outfit, while somewhat embarrassing to wear, turns out to have overpowered stats and effects that make her character significantly more powerful. After accepting the bear equipment, she finds herself transported to another in-game world that prevents her from returning to reality. Confused and unable to log out, Yuna sets out to explore this new environment. She rescues a girl named Fina from wild wolves, who then guides her to the city of Crimonia. With her eccentric bear attire, however, Yuna stands out wherever she goes, and alongside her boosted fighting prowess, her reputation quickly rises—to the point that people give her the nickname Bloody Bear. Undeterred by this change in her life, Yuna decides to take on the role of an adventurer and fully enjoy herself in her new world.