His family had lived in the Tritan mountains for as long as anyone could remember, and even the harsh conditions could not force them to leave…until the Acid Rain era arrived and they could no longer live off the land. His whole family came down from the mountains and became citizens of the Agurts Federation. But Birger never really wanted to leave; he missed the sky, the snow, the quiet mountain peaks. So he joined the 55th Viking Shield Team and became a guardian of the region. Not only did he have to repel raiders, but he also had to guard against animals that couldn't find food and attacked humans, especially those mutated and beastly monsters unique to the Acid Rain era. He sees sorrow and death almost every day, not just in battle, but also when patrolling the borders, observing the bodies of refugees who, trying to escape the war, risked crossing the mountains and ultimately found their doom in the deep snow. Despite the patrols being exhausting and dangerous work - usually assigned to newcomers to toughen them up - Birger leads the team personally every day. If he can save a life on the brink of death, it would be enough. Birger, also known as "Uncle Fossil," is stubborn, tough, and experienced. He leads the newly formed Tritan Guard and trains a new generation of heroes, like the renowned "Snow Leopard" Nelson, who he also rescued. Now, their team has become the first line of defense for the Federation in the vastnesses of the Tritan Mountains.