Kermesita, also known as Koan, is a character who appears in the second season of the Sailor Moon anime, Sailor Moon R. She is a member of the Black Moon clan and the youngest of the four Spectre Sisters, a group of female warriors who serve under the villainous Rubeus. Her name is also sometimes romanized as Kermasite. In the story, she is dispatched from the future to 20th century Tokyo on a mission to locate the young girl Rini and retrieve the Silver Crystal.

In terms of personality, Kermesita is initially defined by her vanity and obsession with her own appearance. She is a cosmetics expert and is highly skilled in makeup and skincare, always striving to look beautiful and well-groomed. She is known for being somewhat intolerant of others and can be unpleasant, but she takes her assignments from Rubeus very seriously and is determined to succeed. Her deep, unrequited love for her commander, Rubeus, is a primary motivator for her actions; she constantly seeks his approval and affection, hoping to be recognized as the most valuable of the Spectre Sisters. However, Rubeus sees her as a failure and openly dismisses her feelings.

Kermesita plays the role of the first antagonist that the Sailor Guardians face in the R season. In her attempt to find Rini, she disguises herself as a door-to-door cosmetics saleswoman and visits the Hikawa Shrine. She eventually discovers Rini and attacks her. This leads to a battle with Sailor Mars, as both fighters wield fire-based attacks. During the fight, her loyalty to Rubeus is used against her when Sailor Mars suggests that his cruel orders are proof that he does not truly love her. When her mission fails, a humiliated Rubeus gives her a black hole device to destroy everything, an act that would also kill her. Desperate and heartbroken, she is ready to use it, but the Sailor Guardians destroy the device. Ultimately, she is saved by the compassion of Sailor Moon, who uses the power of the Silver Crystal to transform her into a kind human being.

Her key relationships are central to her character arc. Her devotion to Rubeus is one-sided and toxic, as he consistently belittles her and shows no concern for her wellbeing. Her initial rivalry is with Sailor Mars, who confronts her both physically and emotionally, challenging her understanding of love and loyalty. After her redemption, she forms a new, positive relationship with the Sailor Guardians, particularly Serena (Sailor Moon) and her friends. She becomes a supportive figure who is especially doting toward Rini and enjoys spending time with the girls.

Kermesita experiences significant development, transforming from a vain and obsessed villain into a redeemed human ally. Her change is prompted by the rejection and cruelty of Rubeus, contrasted with the mercy offered by Sailor Moon. This act of friendship convinces her to abandon her evil ways and start a new life. As a human, she continues her passion for selling cosmetics and remains a friend to the Sailor Guardians.

As a member of the Black Moon clan, her notable abilities include the use of dark fire in combat, which she wields in her battle against Sailor Mars. She also possesses a compact mirror that she uses for her makeup, which also functions as a communication device to receive orders from Rubeus. Her primary method of infiltration involves using her knowledge of beauty products to gain access to new locations.