nagisa and karma are both childhood friends since there were little there parents decided them to settle some arrange married to each other when nagisa started at age of teenagers some reason there parents make an marriage contractions to each other onces there parents agreed to each other by getting married by there children's fate for there future together with karma parents and nagisa parents be together as one family sides even karma never knew this arrange married and make him decided to married to shiota family residents from his own good future as soon he agreed his parents rules to marry nagisa shiota his childhood friend after all nagisa is actually girl who have strong sense when it's comes on her fate ever since there was little kids his parents already make an agreement to the shiota family resident