Ruru is Honoka's deceased best friend and the other half of her mangaka duo "Charles de Macking," who passed away from terminal kidney disease.

Ruru fell in love with Honoka and sought a romantic relationship with her. Even though Honoka reciprocated her feelings, she feared the grief from Ruru's inevitable passing would be too much to bear if they became further involved. Honoka stopped their friendship entirely, leaving Ruru to finish their manga alone.

After her death, Honoka blamed herself for forcing Ruru to work on the last chapter by herself, worsening her illness due to overwork and heartbreak.