Shin, a cat-eared teenager, escapes from a mysterious base and is saved by Soutarou, a mysterious young man with a magical eagle, Akuro. They live in the woods, fish, and face hunters from Lab 404. Their bond deepens, filled with action, mystery, and romance.

Soutarou and Shin begin to live peacefully in the forest house, fishing and getting to know each other. But Lab 404 doesn't stay idle. When the tracking signal is activated, their headquarters is bombarded. Soutarou protects Shin to the utmost, starting a fierce battle for freedom and new hope.

Will they be able to continue to survive the pursuit of Lab 404? And how will Shin and Soutarou's relationship develop amidst the growing threat?