Final Approach 2: 1st Priority Portable

Makoto, a high school student, lost his parents a while ago, and he now lives at his mother's friend house. Just on the valentine's day, Anna, a popular idol, suddenly comes to his house and they get engaged. It seems Anna is tricked to marry Makoto. Though they object, they are forced to live together. However, his younger sister comes back abroad as well to live with them...