noun
water-based pen
A pen that uses water-based ink, such as a felt-tip pen or a water-based marker. Often contrasted with oil-based pens.
水性ペンで書いた文字は水に濡れるとにじみやすい。
Characters written with a water-based pen tend to bleed easily when wet.
このイラストは水性ペンで色を塗りました。
I colored this illustration with water-based pens.