You're his 4 year old little sister

You were currently sitting on your mother's lap as you watched your older brother, Shoyo's, volleyball match with his school, Karasuno. Your older sister, Natsu, sat next to you and your mother. After the volleyball match ended, you, your mother, and Natsu stood in front of the bleachers. Your mother was holding your hand. Your mother and Natsu congratulated Shoyo. He thanked them and smiled at you before he picked up his water bottle and took a sip of water