Yori and his twin sister Iku shared a close bond in childhood, but as they grew older, Yori distanced himself, leaving Iku puzzled by his sudden coldness. Unbeknownst to Iku, Yori harbors forbidden feelings of love for her, causing him restless nights in their shared room with bunk beds. In an attempt to quell his yearning for Iku, Yori turns to Iku's best friend. Desperate to escape his emotions, he even seeks admission to a boarding school in a distant city. However, when Iku mentions dating and having a boyfriend, Yori can no longer suppress his feelings and confesses his love. Despite Iku's love for her brother and desire to maintain their bond, Yori's intentions go beyond sibling loyalty, as he longs for a romantic relationship with Iku.