Yuu Matsumi

As the central protagonist of the "Saki Achiga-hen episode of side-A" spin-off, this third-year student at Nara's Achiga Girls' Academy navigates life alongside her younger sister, Kuro. Though she initially hesitated to join the school's mahjong club due to fears of being too old for the group, she eventually became a key member. Notably, she possesses an extreme sensitivity to low temperatures, often wearing heavy, full-body layers regardless of the season.