I thought it's only French and Dutch that call public urinaries "Vespasiennes", but it's listed in Wikipedia as an optional name for pissoir in English as well.
Had to check the raws to make sure they were joking.
Volume 2 came out a month ago. So he’s going to find some way back to the isekai world - likely by being flushed down a toilet or something - and go on more adventures.