Thermae Romae

When Roman architect Lucius is criticized for his “outdated” thermae designs, he retreats to the local bath to collect his thoughts. All Lucius wants is to recapture the Rome of earlier days, when one could enjoy a relaxing bath without the pressure of merchants and roughhousing patrons. Slipping deeper into the warm water, Lucius is suddenly caught in the suction and dragged through the drainage at the bottom of the bath! He emerges coughing and sputtering amid a group of strange-looking foreigners with the most peculiar bathhouse customs... over 1,500 years in the future in modern-day Japan! His contemporaries wanted him to modernize, and so, borrowing the customs of these mysterious bath-loving people, Lucius opens what quickly becomes the most popular new bathhouse in Rome—Thermae Romae!
(Source: Yen Press)
Note: Won the 3rd Manga Taisho Award in 2010.