We developed the world’s first wet-type capacitive brush stylus, which completely solves the long-standing realism problem in capacitive brush styluses and fulfills the goal of writing calligraphy and painting with a real brush pen on capacitive touchscreens. Through our study of capacitive touch materials and their operating principles, we found that materials with higher capacitance exhibit greater touch sensitivity. Materials with thin thickness, large surface area, and high dielectric constant tend to produce higher capacitance, and thus serve as excellent capacitive touch materials. This finding challenges the conventional assumption that capacitive touch materials must be conductive or electrostatically transmissive. Unlike commercial brush styluses that use conductive fiber tips, our design directly converts a real brush pen into a touch stylus. By utilizing the high-sensitivity touch responses of moistened brush hair and integrating capacitive series-parallel coupling through conductive patches on the brush handle, we successfully developed a full-realism passive capacitive brush stylus. This innovative design reproduces the same brush elasticity, brushstroke dynamics, and artistic effects as a real brush pen, achieving the highest level of realism among existing capacitive brush styluses. Moreover, the fabrication process is simple and requires no external power, offering the advantages of energy efficiency, low cost, and high compatibility with current capacitive touchscreen devices.