If not for the incest this was a wholesome manga. In fact quite refreshing, showing a couple gradually finding their way from faux-love to marrige.
Of course, the incest also exists. The story did at least use the incest to create meaningful story arcs about getting acceptance from the people around them. It was pleasant to see parental approval as the final "boss" of the story and not something such as exams or past trauma. The incest is certainly not my thing and I do question the young age they started going out (15) although more progressive trends within society give greater autonomy to teenagers to do as they wish. If the two had genuine love for each other and neither was manipulated by outside agents, who is any one around them to deny their expression of love?
7/10.