Yuzuru Shiga leads an ordinary life, dedicating most of his time to his high school archery team alongside his girlfriend, Satomi. However, his relatively mundane existence becomes complicated when his aunt dies under suspicious circumstances and his cousin and fiancée, Azusa, re-enters his life. While Yuzuru views her as merely a relative, she is dangerously serious about their future marriage and will not tolerate the threat posed by Satomi. As events grow increasingly strange following Azusa's return, Yuzuru must now decide whether his relationship with Satomi is worth the potential danger.