Brothers Conflict: Brilliant Blue is a dating simulator set in Japan. It is one of Otomate's two games in the series, the other being Brothers Conflict: Passion Pink. The difference between the two games is that owing to the numerous choices and prospects, the various love interests you may have are different.

Hinata Ema is a sixteen-year-old girl who has spent the most of her youth living alone. She has lived alone with her father, Hinata Rintaro, since she was a child because of his career as a famous adventurer, which takes him all over the world. Her father had recently gotten engaged to a woman called Asahina Miwa, and Ema was expecting thirteen siblings as a result. However, as the siblings and Ema get to know one other, the brothers, who are all male, develop love for her despite the fact that she is their new "sister."