Once again we find ourselves in ancient Rome at the time of Emperor Hadrian’s rule. The now famous bathhouse architect Lucius (Hiroshi Abe) is commissioned to rebuild/redesign the bath facilities in the colosseum, which now provide ample relief from the aches and pains the gladiators face. While observing the dank and gloomy thermae, Lucius realizes that he is without innovative ideas as to bring about his own bathhouse philosophy. While thinking hard, he suddenly slips again through time and resurfaces in a sumo wrestlers bathhouse in Modern Japan. Mami (Aya Ueto), who is now a writer covering bathing culture – even though she has not given up on her dream of becoming a manga artist, quickly reconnects with Lucius in his quest for innovative ideas.
Back in ancient Rome a political confrontation is brewing. Some senators, who favour a strict expansionist policy, want Emperor Hadrian (Masachika Ichimura) and his pacifist position gone. Hadrianus asks Lucius to build a thermae than will ensure peace in the Roman empire. Are the senators able to stop Lucius in his quest of building a peace ensuring bathing paradise?