Kizaši no wákuauto! (S03E05)

The Iwatobi High School Swim Club is participating in a joint training camp with the Samezuka Academy and Soufuukan High School teams. Sousuke is also participating as an alumnus. In the midst of the excitement, Rei and Nagisa notice that something is odd about Romio's swimming. Then Shizuru tells them the story of what happened to Romio in middle school... (Crunchyroll)