Lucio Modesto, a Roman architect specializing in bathhouse design under Emperor Hadrian, struggles against creative stagnation early in his career. This professional rejection coincides with personal turmoil: the dissolution of his marriage to Livia. Her departure stems from prolonged absences due to imperial duties and misunderstandings regarding his relationship with Hadrian; Livia leaves while pregnant with another man's child. A pivotal accident traps him in a bathhouse conduit, displacing him into 20th-century Japan. This unintended time travel recurs, exposing him to advanced Japanese bathing technologies and customs. He observes modern shower systems, water filtration, and recreational bathing practices. Inspired, he adapts these concepts using Roman materials—stone, wood, leather—creating innovations like ramune-styled bottles, leather shower circles, and rudimentary water wheels. These designs revitalize Roman bathing culture and earn imperial recognition. Emperor Hadrian becomes his crucial patron, commissioning projects empire-wide. Their professional bond evolves into mentorship, with Hadrian offering strategic counsel during political instability. Lucio witnesses Hadrian's final moments in the Baiae baths, receiving the emperor's last words. Later professional challenges arise under Commodus, whose decadent aesthetic preferences clash with traditional Roman design. During extended stays in modern Japan, particularly Ito, Lucio gradually adapts to contemporary life. He forms a significant bond with Satsuki, a Japanese woman fluent in Latin due to her academic background in Roman history. Their relationship deepens when Satsuki voluntarily journeys back to ancient Rome to reunite with him. They build a life together, raising a son named Marius and integrating elements of Japanese culture into Roman society. Twenty years later, under Marcus Aurelius, Lucio faces renewed challenges. Advancing age imposes physical limitations, compounded by Satsuki's unexplained disappearance. His son, Marius, grows unmotivated, showing little interest in the architectural legacy. Roman society transforms: bathhouses devolve into centers of debauchery, and the Colosseum hosts increasingly brutal spectacles, reflecting broader imperial decline. Lucio's design philosophy shifts from directly replicating Japanese innovations to nuanced adaptations tailored to Roman contexts. Early projects display creative sterility through literal copying; later works demonstrate greater integration of observed principles with local materials and traditions. This approach achieves temporary revitalizations of Roman bath culture, though these eventually deteriorate amid the empire's moral and political decay. Personal relationships significantly shape his professional path. Initial isolation gives way to meaningful connections, including Marcus as a loyal friend and collaborator. Lucio embodies traditional Roman values but exhibits adaptability, adopting Japanese social bathing customs. His physical presence includes a distinctive stoic demeanor and notable hair color variations, details secondary to his documented narrative arcs.