Update May 2018
Kuretake products can NOT be considered vegan-friendly.
At first Kuretake representatives assured me, that their products are cruelty-free, they later chose to inform me, that, due to the language-barrier, they are not able to understand what cruelty-free means or what animal-testing is. Despite claiming to have a looked into this matter, no more replies followed.
Vegan friendly products: -Kuretake Fude Pens, except the Fountain pen Shikatsuno series, the Fountain Brush pens have a brush tip made of animal hair -ZIG Cartoonist Ink, except the Sumi Ink -ZIG Kurecolor –ZIG Clean Color Real Brush -ZIG Waterbrush H20 -Acrylista -Gansai Tambi including the Pearlescent and Starry Colours
I am happy to finally share this information with you. The list is still incomplete, there will be additions over time.
Source: Mail contact