Potsupotsu (Pitter-Patter) – the color of icy lilac during a brisk winter rain. The name of the ink color is embossed on each cartridge and come in a pack of eight. Each cartridge set comes in its own white portable carrying case. Sailor fountain pen ink cartridges are proprietary, and only fit Sailor fountain pens that accept cartridges. Designed as companion inks to the Sound of Rain fountain pens that Sailor released in 2021, these inks are named for the different sounds that rain makes as it falls.