This is the hilarious story of Lucius Modestus, a public bath architect in Ancient Rome. For unknown reason, he finds a secret aquatic time portal that leads him to a present-day Japanese Sentou (public bathhouses with hot springs and bath tubs). These facilities give him inspiration for his buildings and he learns many things from Japanese modern ingenuity and technology such as drinking fruit milk after a bath, scrubbing towels, and shampoo hats. He makes what he learned real in Roman baths after he comes back to Rome and he gradually gains a lot of fame.