The Pentel Color Brush is a color brush pen with a brush-shaped tip. Like a real brush, it can change line width as you draw, and the colors are bright. The standard colors use water-based dye ink. The fluorescent colors use water-based fluorescent pigment. When the ink runs out, put in a new cartridge (a tube filled with ink, sold separately) and keep using the pen.
The range has 30 colors: 24 standard colors and 6 fluorescent colors. Each color is sold on its own, and there is also an 18-color set.
Mix two colors to make a gradient. Or blur the color with water or a water brush (a brush with water in its barrel) for a watercolor look.