Yuna Tachibana is a central character in the anime series 'Tsundero.' She is known for her tsundere personality, which means she often alternates between being cold and hostile, and warm and loving, especially towards the protagonist. Yuna is a high school student with a strong sense of justice and a passion for helping others, even if she struggles to express her true feelings. Throughout the series, Yuna's character develops as she learns to open up and trust her friends, playing a crucial role in the storyline.