Seijuro Mikoshiba (御子柴 清十郎 Mikoshiba Seijuurou) is a supporting character in the anime series Free! beginning with Free! He is a butterfly swimmer and Captain of the Samezuka Swimming Club until he graduates, at which time he bestows the position onto Rin Matsuoka. He is currently a third-year university student at Hidaka University, where he is a member of the Hidaka University Swim Club alongside Haruka Nanase and Asahi Shiina.