Thirteen-year-old Umeda Mika is a homeless orphan girl living in the slums of the Arakawa-ku district in Tokyo, Japan. Due to her rough upbringing, her body refuses to grow without proper nourishment. Often referred to as "Loser Dog" Mika will do just about anything to ensure she has a decent meal; even if that means stealing from the Yakuza. Mika's life changes in an instant when she gets kidnapped by the Bara-gumi, the Rose Group, and forced to become the loyal servant of Ninagawa Charlotte, their ruthless leader with an iron fist.