Thermae Romae
The Fascination of Pharos / I Want to Slip Honestly
S1 E4:
Marcus goes to see Lucius and finds him in a deep depression. A trip through a cauldron to Japan snaps him out of it, but not in the way he expected. Emperor Hadrian orders Lucius to build a new public bathhouse. While reflecting on it's design, he winds up in a Japanese water park.