Yuri Briar is the brother of Yor Forger. Both of them grew as orphans with Yor working to keep Yuri studing. Yuri eventually entered to work for the Secret Police of Ostania (the SSS), a fact he keeps secret from her sister.
Yuri have obssesive freudian feelings for her sister and is not happy with her marriage with Loid Forger. Unaware to him, his sister is a killer for hire and his brother in law is Twilight, the spy who Yuri wants to capture the most.