Ideal Girlfriend

Saeki is an ordinary high school boy with a girlfriend, Sara, who is the heiress of the Saionji Group, and whose beauty and intelligence are the envy of everyone. Sara seems like a prim and proper young lady to other people, but the two share a secret! Because of the secret, Saeki can't fully commit, but Sara prepares lunch for him, she hugs him to deepen their relationship, and she acts like she's trying to seduce Saeki to corrupt him!!!? What is the secret of their relationship and what is Sara's true purpose...!!?