Description:

S-Rank adventurer and second-generation sword saint, Ryunoa Styler, is reunited with his childhood friend, Aine, who has been reduced to slavery. Ryunoa purchases Aine in order to save her, however, she's been given a cursed collar that causes the wearer to go into 'heat' once a day... Ryunoa's battle to find a way to remove the collar starts now! (Source: MU)

Alternative Titles:

一緒に剣の修行をした幼馴染が奴隷になっていたので、Sランク冒険者の僕は彼女を買って守ることにした, Issho ni Ken no Shugyou wo Shita Osananajimi ga Dorei ni Natteita node, S-Rank Boukensha no Boku wa Kanojo wo Katte Mamoru Koto ni Shita