The Female Professor Is the Big Sister Next Door!

When Gu Yun was in junior high school, a mother and daughter moved in from their neighbor, and he met his eldest sister Yu Ning. Yu Ning: "Does my little brother like my sister?" Gu Yun: "I like it!" Yu Ning: "Will my little brother be with my sister in the future?" Gu Yun: "...... Yes." Three years later, when he entered high school, Yu Ning completely disappeared from his world as if he had evaporated. It wasn't until Gu Yun went to college that he met the beautiful professor Yu Yanning of the college by accident. Yu Yanning: "Classmate Gu Yun!" Gu Yun: "... Here" Yu Yanning: "Do you want to be my class representative?" Gu Yun: "I want..." Yu Yanning: "Does classmate Gu Yun still like her?" Gu Yun: "I like it!" Yu Yanning: "Then does Gu Yun like me?" Gu Yun: "?" Gu Yun: "My love for Sister Yu is unwavering!" Yu Yanning: "Then guess who I am?" Are you...?