Riku, the only son of a mansion who lost his mother at a young age. Later on, he starts living with Maria, the heroine who is the stepchild of the former maid mother, Mako, from his father's remarriage. Under Mako's influence, Maria becomes Riku's exclusive maid and they start living together. Several years later, Riku and Maria, who have spent a long time together, start to become aware of each other as the opposite sex. In the midst of this happiness, their father suddenly passes away. With the master of the mansion gone, various men start approaching with different intentions. To protect Riku from these malicious men, Maria struggles, but the men gradually begin to target Maria and start using various means to approach her. Will Riku be able to protect Maria, his family... and the mansion?​