The Tachikawa School G is refillable, fast drying waterproof, & Copic-proof. It's great for calligraphy & manga/comic creation. *This pen is intended for frequent use & can dry up if left unused for 1–2 weeks. If the pen does dry up, soak the tip in water to revive it. If the pen is left dried up for more than 3 weeks, it can become permanently damaged.