Beryl Gardenant, an aging swordsman who runs a modest dojo in a rural village, is someone who prefers to spend her life as calmly and smoothly as possible. However, once the doors of the past are opened, the silence does not last long. With the unexpected visit of her former student and the Royal Knights, Beryl's village tranquility begins to give way to a much bigger scene. The crux of the series lies in the main character's distinct departure from classic isekai or fantasy heroes. Beryl is not young, ambitious or trying to prove herself; On the contrary, he is an ordinary-looking middle-aged man who has withdrawn from the world and avoids noise. However, behind this mediocrity is hidden a mastery spread over many years. The humor of the series is largely fueled by this contradiction: While everyone around her is unaware of her true power, Beryl continues to maintain her modesty, being aware of everything. Following the lines of Seinen, the production leaves enough room for the relationships between characters and the warmth of daily life, as well as exaggerated shows of power and epic battles. While the action scenes are drawn with satisfying elegance, the story never takes itself too seriously. It offers the audience both an entertaining fantasy adventure and a thought-provoking experience about the "power of the invisible". It is perfect for viewers who are overwhelmed by grand epic narratives but do not want to break away from the fantasy world.