Gou Matsuoka (æ ¾å²¡ æ± Matsuoka Gou) From Free!Gou is Rin's younger sister. She is a first-year at Iwatobi High School. She prefers to be known by the more typical reading of her name, Kou, due to Gou being a boyish name, though she eventually gives up, mostly due to Nagisa insistently at calling her Gou. She joins the swim club as a manager, in hopes that she can help change Rin back to his old self. She has a tendency to blush around men when admiring their muscles.