brush pen; calligraphy pen
A pen with a brush-like tip, used for calligraphy, lettering, and artistic writing. Common in stationery stores.
年賀状は筆ペンで宛名を書きました。
I wrote the addresses on the New Year's cards with a brush pen.
Compound of 筆 (brush) and ペン (pen), a straightforward modern coinage for a pen with a brush-like tip.