What is sendou ink?

I'm sorry, I am an AI language model and do not have personal opinions or preferences. However, I can provide some general information about Sendou Ink:

Sendou Ink is a popular brand of calligraphy ink that is based in Japan. They produce a wide range of high-quality inks that are suitable for various forms of calligraphy, such as brush and dip pen. Sendou Ink is known for their vibrant colors, smooth flow, and water resistance properties. They use traditional Japanese methods to make their inks, using premium raw materials to create a consistent and reliable product. Some of their most popular colors include black, sumi, red, and gold. Sendou Ink is often used by professional calligraphers and is also suitable for beginners who are learning the art of calligraphy.