The character known as Auntie, Oba-Chan, or the Landlady is formally named Mine Nakahara, and she is the paternal aunt of the protagonist, Sunako Nakahara. She is a figure of immense wealth and eccentricity, often referred to as the infamous Marie Antoinette of the East due to her extravagant lifestyle and commanding presence. Mine is the younger sister of Sunako's father, and she is the owner of the large mansion where both her niece and the four handsome young men live. Her backstory includes the loss of her husband, and while she frequently travels to places like France with a series of new boyfriends or fiancés, this behavior stems from a sense of loneliness. She does not truly love any of these men in the same way she loved her late husband.

In terms of personality, Mine Nakahara is depicted as tall, beautiful, and haughty with a very imposing demeanor. She is extremely wealthy and often makes her grand entrances in unconventional ways, such as arriving in a fleet of helicopters. Despite her glamorous and sometimes intimidating exterior, she shares a deep, caring bond with her niece. Her personality also carries a formidable edge; like Sunako, she requires very little effort to frighten the four boys, commanding a natural authority over them. She is also notably multilingual, with the ability to speak fluently in languages such as French, Russian, and Filipino.

Mine's primary motivation throughout the story is the happiness and well-being of her niece, Sunako. She believes that the best way to achieve this is to transform Sunako into a proper lady. This desire is rooted in Sunako's childhood, when she looked up to her aunt as the most beautiful woman in the world and expressed a wish to be like her. The tragic rejection that turned Sunako into a dark-loving recluse is what spurs Mine into action. To achieve her goal, she makes a deal with her four tenants, the handsome Kyohei, Takenaga, Yuki, and Ranmaru. She offers them free rent to live in her mansion on the condition that they succeed in turning Sunako into a perfect lady within a set time frame, often threatening to triple their rent if they fail.

In the story's narrative, Auntie serves as the catalyst for the entire plot. Her deal with the four boys sets the premise for the series, forcing the interaction between the reclusive Sunako and the creatures of light she despises. Her role is often that of an off-screen but ever-present authority figure. Because she is frequently traveling, the boys usually have to convince her that Sunako is on the fast track to becoming a lady, which is far from the truth. This leads to her unexpected visits becoming major events, during which the boys must scramble to put on elaborate acts and disguise Sunako's true, morbid personality to avoid her wrath and the raising of their rent.

The character shows notable development in her relationship with Sunako and her understanding of what a lady truly is. While their direct interaction is somewhat limited, it is clear that her love for Sunako is genuine and that she simply wants her niece to be happy. As the story progresses, Mine gradually shifts her focus away from rigidly trying to shape Sunako into a traditionally elegant lady. She comes to believe that Sunako is perfectly capable of acting like a lady when the situation truly demands it. Her attention then turns toward Kyohei, the male lead, as she attempts to mold him into a suitable partner for her niece. In a significant moment, Sunako teaches her aunt that a true lady is someone who never compromises her beliefs, someone who can be proud of the things she loves, and someone who can shine without dresses or makeup. This redefines her understanding of womanhood, moving beyond superficial expectations.