The story takes place in a small city called Xingyuan City. On the Lion's Tail Mountain within the city stands a giant object that shines with colorful light, known as the "Horn of Mono". This object has actually been standing there since the "Day of Monsters" event 16 years ago when monsters appeared around the world simultaneously. After the "Day of Monsters" incident, monster disasters started to become a regular occurrence. While Japan's Earth Defense Force began to confront monsters with military force, the Monster Disaster Prevention Scientific Investigation Institute (commonly known as SKIP Scientific Kaiju Investigation and Prevention Center) continually conducted scientific investigations and evacuation guidance in various regions to prevent further monstrosities and mitigate disaster. To this day, this organization is still investigating the causes of the "Day of Monsters" and the "Horn of Mono" in the city. Seven-year-old "Yuma" was camping with his parents on Lion's Tail Mountain when he encountered a monster attack; miraculously, he survived unharmed. This experience set him on a path to study monster biology. Although he has a painful past...
