Kōsaku Sakamoto ( 坂本 耕作 , Sakamoto Kōsaku ) is the protagonist of Stop ! ! Hibari @-@ kun ! ! and is originally from Kumamoto.Ch. 33 He is a pure @-@ hearted high school student who constantly refuse Hibari 's advances toward him , Ch . 2 , 3 , 10 , 17 but as time go on , he become increasingly concerned that he is being influenced by Hibari.Ch. 8 , 22 , 35 , 38 Kōsaku treats Hibari kindly , and help to maintain Hibari 's secret.Ch. 25 , 50 , 51 Initially unskilled at fighting , Ch . 3 he join the Wakaba Academy boxing club in an effort to get stronger because of Hibari 's inherent strength , Ch . 8 which he achieve as the series progress.Ch. 38 Kōsaku is voiced by Tōru Furuya .