In a real cell, droplets are generally generated under stimuli such as protein expression, accumulation, RNA translation, and epigenetic DNA modification and serve as reaction fields and for material storage. Then, their disappearance is triggered by unknown reasons (Figure ), although local temperature changes or accumulation of metabolic products have been proposed as responsible. The droplet formation/disappearance process is essentially a nonequilibrium process. Some theoretical studies and molecular dynamics simulations have addressed this dynamic process; however, experimental models to reproduce the droplet formation/disappearance process in vitro are scarce.