Japanese pigment inks are made according to the rules of the art and in the spirit of Japanese culture. Platinum has already made a name for itself with its pigment inks.
Pigment ink is an ink based on pigments and developed for fountain pens. Pigments do not dissolve in water but adhere to a carrier. That is why they are waterproof and permanent.
You can safely use pigment inks in your fountain pen if you observe the following rules:
Make sure you have a fountain pen with a tight cap, and write regularly with your pen (preferably every day).
Clean your pen regularly with tap or distilled water. If you write once with this ink, clean the pen after use.
Flush water with a rubber bulb, or use a convertor and repeat until everything is clean.
If you change to another type of ink (standard or iron gall), make sure you COMPLETELY CLEAN your pen with pigment ink.