On the first day at a new school, a tough-looking transfer student who marched in ready to intimidate everyone finds himself seated next to a student wearing a complete suit of samurai armor. The armored figure turns out to be a gentle and attractive girl, and the yankee bully, whose intimidating demeanor is largely a front, is thrown into a series of bewildering and comedic situations as he tries to navigate ordinary high school life beside someone who never removes her helmet. The manga follows their odd-couple relationship, blending slapstick humor with a developing romantic tension, all set against the backdrop of a seemingly normal Japanese high school that has accepted the presence of a permanently armored student. The armor itself is based on a real historical piece once associated with the Sanada family, adding a layer of quirky authenticity to the premise. As the story progresses, the armored girl’s hidden personality and the reasons for her unusual attire gradually come to light, while the delinquent protagonist’s softer side emerges through his interactions with her and the classmates who react to the bizarre situation with varying degrees of surprise and amusement. The narrative focuses on everyday school events, misunderstandings, and the gradual, awkward bonding between the two leads, with the armor serving as both a literal barrier and a catalyst for their unique connection.