Recent protein engineering methods using IDR or continuous folded domains have successfully induced artificial droplet formation in mammalian cells . In comparison, our peptide-based approach exhibits several advantages. First, our peptide enables the fine-tuning of droplet dynamic properties by simply adjusting peptide length. Second, its small size, namely 9-15 residues, significantly streamlines experimental procedures at the laboratory scale . The YK gene can be incorporated at desired positions by inserting annealed oligo DNAs or via inverse PCR using primers containing a peptide gene. Third, owing to its homotypic interactions, our approach enables the design and construction of multi-component droplets. Consequently, this study emphasizes the universality of de novo self-assembling peptides within cells.