Kyousei (a Touhou LW original) refers to stars of ill omen. An apt temperament for Joon, the most-despicable and disastrous younger twin sister. Joon is endowed with Fire Phase, since she is a spendthrift harboring a burning passion, and Star Essence, with her lack of patience. The formless and passionate Fire Phase resists Wood Phase, because wood feeds fire, but it is weak to Water Phase, because water dampens fire. The diverse and uncooperative Star Essence resists the cooperative and indecisive Moon Essence, but it is weak to the charming and arrogant Sun Essence.

Joon's ability seems to act through possession. By possessing her target and appealing to their subconscious, she makes them believe that they are giving her offerings of their own free will. The targets of this ability do not only lose all of their financial assets but also all of their luck. Joon has continued to bestow this terrible fate onto countless people―getting rich at their expense. Furthermore, it is said that the loss of luck inflicted by this ability can transmit to others, causing the victims' friends and family to lose luck also. The Ruler of Dreams told Joon that she "Truly wants to live a modest life," leading Joon to have a change of heart and train under Byakuren after the incident Joon instigated was resolved. Though it seems that her time training at the temple was short-lived, as she has returned to extorting money from people in the Human Village... Albeit, she now only does so in a way that does not cause misfortune for anyone.