"All the Important Things I Learned in a Bathhouse" (大事なことはぜんぶ銭湯に教わった Daiji na Koto wa Zenbu Sentō ni Osowatta?) is the first OVA for the Toaru Kagaku no Railgun S anime series. It was first released on March 25, 2014, bundled together with the Toaru Kagaku no Railgun S Official Visual Book.