Mary returned to her hometown after a long time living in Tokyo. Since his parents were away, only his younger brother Takashi was at home to welcome Mary. Unexpectedly, in just a few years, her sister has become an extremely charming woman! Takashi couldn't take his eyes off Mary's hot body. Knowing that his sister is extremely naïve and trusting, Takashi decides to trick Mary so that he can fuck her! He lied that women who did not have sex within three years would close their hymen and return to being virgins, which was called "second virginity". Afraid of the feeling of losing her virginity for the first time, Mary asked Takashi to check on her. Just waiting for the possibility, Takashi immediately committed his misdeeds with his innocent sister...