Matsuri Shiina

As the devoted older sister of Aki, Matsuri Shiina plays a nurturing and deeply affectionate role within the story. Her personality is defined by her doting nature, as she constantly prioritizes Aki's well-being and maintains an incredibly close, protective bond with him. This central sibling relationship serves as a key emotional pillar, showcasing her selfless dedication and the warmth she brings to every interaction involving her younger brother.