Sakura Pigma Micron Pen - Blue, 02 (0.3mm)

The Micron is the reference point for technical drawing pens, and the blue is a quieter alternative to black for underdrawing, annotation, and anything you want legible but not loud.

Archival pigment ink: waterproof once dry, fade resistant, and stable enough to sit under watercolor without lifting.

The 02 nib holds 0.3mm reliably, which matters if you are working small.