In the fantasy world ruled by Matriarchy, Kael of the Ancient Moonstone House, was working as a guild receptionist. Throughout his life, he was protected by his mother and later, younger sister, who was considered one of the highest potential individuals in the Queendom of Elyria. One day, he hears that his sister has gone missing and his family has accumulated debts of over 127 million gold coins to the Bank. The Queen comes to his rescue, paying off his debts and in exchange, he has to marry her five daughters, who each excel in a domain of their own.Having the five imperial princesses and the Queen herself as the backing, Kael has become one of the most protected individuals in the Queendom. Little did his wives know that Kael had another identity. He is the most dreaded yet noble Assassin of the imperial city, “K,” one who hunts down the criminals who escape punishment either because of insufficient evidence or using their connections.Follow Kael's journey, as he navigates his life as the protected figure in the light and protector of justice in the shadows.