In the past, the asteroid Kumaria detonated in the vast expanse of space. As a result, fragments from the explosion showered down on Earth, sparking a strange phenomenon where bears worldwide began to rise against humanity. This conflict between "Man vs. Bear" saw both sides engage in a deadly cycle of eating and shooting each other, fueling a deep-rooted hatred. However, a colossal "Wall of Extinction" was ultimately built to divide the two, leading to a state of uneasy peace.
In the human world, Arashigaoka Academy pupils Kureha Tsubaki and Sumika Izumino are spending some quality time together when they spot the "Yuri Flower" blossoming in a flowerbed. These two are friends as well as lovers, and this particular area holds a special place in their hearts. Suddenly, the Bear Alarms go off, signaling that the bears have breached the human world and are attacking. But are these animals truly the same bears that have been waging war with humans for so long? One mystery leads to another, and the plot thickens as their investigation deepens.