The B Rank Missions are only assigned to to experienced ninja. With these missions you are able to unlock villians and subordinates of the most dangerous ninjas.
Win 3 battles with Hyuuga Hinata versus any Ninja of the Sand Genin (Gaara, Kankuro, Temari). (3/3) Win 3 battles with Aburame Shino versus any Ninja of the Sand Genin (Gaara, Kankuro, Temari). (3/3) Win 3 battles with Inuzuka Kiba versus any Ninja of the Sand Genin (Gaara, Kankuro, Temari). (3/3)