This is a new anime that I’ve been watching recently, and it’s hilarious. It’s about a guy in ancient Rome called Lucius who is an architect responsible for designing the empire’s public hot spa baths. He gets criticized by the emperor for having ran out of ideas and inspiration for how to develop the bathing culture further and reflects on this during a hot bath when suddenly he’s pulled underwater by a mysterious force. When he resurfaces he finds he has warped to present-day Japan and finds himself either in a Sento (public bath) or an Onsen (natural hot spring) or some other location particular to the Japanese bathing culture, depending on the episode.
During his short time there he picks up ideas and is routinely astounded at the technological advancements he sees. After warping back to Rome he employs the ideas in Roman baths and becomes the toast of the empire. For each episode, rinse and repeat!
NOTE: As of writing this post, you can watch episodes on Dailymotion.com.