Illusion of the Cherry Blossoms

Should you sell dreams? Buy dreams? Or…?

Oiran (courtesan), the business of selling dreams.
Though he reigns at the top of his courtesan profession, Tankou leads a boring life.
While gazing at the fleeting yet beautiful…and hateful cherry blossoms blooming before his eyes, a mysterious person named "Yoru" appears.
Who on earth is she?