In contrast, the disappearance of droplets was observed near the opposite side boundary (Figure ). Large droplets moved toward the ATP-rich area and then disappeared (Supplemental movie 2). Larger droplets moved faster (Figure ), indicating that the velocity of droplet movement depends on the droplet radius (Figure ). Although the reason for the droplet motion remains unclear, this observation suggests that the motion of larger droplets stems from Marangoni convections on the droplet surface, while smaller droplets flow with the diffusion of ATP from the less viscous ATP solution to the PLL-rich direction. Our analysis suggests that the speed correlates with the droplet radius (Figure ) and it supported the occurrence of Marangoni convection in our system. Note that some very small droplets moved in the opposite direction, against the ATP concentration gradient. Thus, we concluded that the smalls flowed with the usual diffusion of ATP toward low-concentration regions (Supplementary movie 2). This observation-based phase-diagram modeling constitutes the profitable strategy to construct experimental handy model of the nonequilibrium process of droplet formation/disappearance, which could be applied to outward materials such as proteins, nanomaterials, and their complexes for the analysis of their interference on the LLPS process in real cells.