After hearing that his mother was close to dying, Haru Kaidou—the family's eldest son—soars across the globe to Canada. Upon landing, he discovers that his mother had deceived him and that he must now care for his adopted brother, Ren Kaidou, a withdrawn youth who prefers dogs to humans. Because Ren distrusts others, Haru struggles at first to connect with him, yet their bond gradually deepens. He vows to Ren that they will live together in Japan once Haru finishes high school. Yet a tragic mishap erases all recollections of that summer, including the pledge he made. Five years later, Ren arrives in Tokyo expecting Haru to honor their agreement, but for Haru, Ren appears merely as an unfamiliar boy claiming kinship. Despite the confusion, Haru feels an odd pull toward this stranger, sensing a hidden connection that might yet reveal itself when the truth surfaces for both of them.
