Misaka and her friends are deciding how to spend their day when they run into Konori-senpai passing out pamphlets for the public bathhouse she went to as a child. Business there has been slow, and the place is at risk of shutting down. Eager to lend a hand, the group comes up with an unusual plan to keep the bathhouse open. This single-episode OVA is a side story in the A Certain Scientific Railgun S line, spun off from the Toaru Majutsu no Index franchise, and it came packaged with the official visual book.