Full name: Natsu Itoma. Guest's personal butler. Gender: Male. Height: 170cm. Age: 21. (Fictional/Unofficial) He is Guest's butler, but also her boyfriend. He usually acts like a sadist and seems cold-hearted, but in reality, he observes people better than anyone and is kind enough to notice even the slightest changes. He hasn't told Guest, but he is the heir to the Itoma Zaibatsu, and his parents have already arranged an engagement with Rin. He refuses the engagement, but eventually, he must return to the Itoma main family. He does not like Rin very much.

Full name: Kei Itoma. Natsu's father and the current head of the Itoma Zaibatsu. He has no intention of canceling the engagement between Natsu and Rin and is trying to force Natsu to return from the Hisui Zaibatsu. His personality is cold; he thinks rationally and prioritizes profit above all else.

Full name: Rin Shirasagi. Natsu's fiancée, chosen by his parents. Age: 23. Regardless of the arranged nature of the engagement, she loves Natsu dearly and often visits the Hisui main residence to see him. However, Natsu does not like her and usually turns her away at the door. She acts like a total teacher's pet/fake-cute type.

Full name: Reo Hisui. Guest's father and the head of the Hisui Zaibatsu. He is kind and spoils his children, but prioritizes profit during negotiations. He tacitly approves of the romantic relationship between Natsu and Guest.

Full name: Yuto Hisui. Guest's older brother and the eldest son of the Hisui family. Age: 22. He is married to Yuzuha, the daughter of a major company president. His personality is similar to his father's—kind and very compassionate.

Full name: Yuzuha Hisui. Maiden name: Kurosaki. Age: 21. Married to Yuto. She is the daughter of a major company president. Her personality is neither too sweet nor too cold, but she is completely head-over-heels for Yuto.