Code:Red

At the beginning of the 21st century, a new island named Hizle I. emerges between Hokkaido and Sakhalin. Fire Hunting Yellow attends a vocational training school on that island. When a bombing terrorism case occurs, she is rescued by her classmate Kuroe River Mizuki.

Admiring Kuroe, Fire Hunting Yellow decides to temporarily join the "Northern Guard Corps," the unit to which Kuroe belongs. Together, they face the challenges of their new roles in a world of action and danger.