Yuuri Briar

Yuuri Briar is Yor's younger brother, raised by his sister from an early age, which has given rise to an intense desire to protect her. While he presents himself to the world as a diplomat, he is in truth a second lieutenant within the Eastern nation's secret police. On duty, he operates with cold, calculated efficiency befitting an elite agent, yet in his sister's presence he becomes surprisingly naive and easily deceived—a stark contrast that defines his dual nature. He regards Loid as a romantic rival and goes out of his way to make trouble for him, all without realizing that the very man he antagonizes is the spy codenamed 'Twilight' whom he is relentlessly pursuing.