In the world of structural perfection, Xyloise is the ultimate "calculation error." An aspiring architect with a chaotic life and a blunt tongue, she finds herself under the cold, unyielding supervision of Architect Waeren—a man whose life is built on strict blueprints and zero tolerance for mistakes. Their worlds collide when a literal mess leads to a professional debt, forcing Xyloise to work as his personal assistant. Between midnight deadlines, coffee-stained floor plans, and silent elevators, Xyloise begins to realize that Waeren’s "reservations" aren't just about his projects—they’re about his heart.