It is a style of minimalistic art, using ink and wash painting. Only one color of ink is used, but the ink is washed out in areas to create shadow and depth.

It is known as a wash, especially in water colour painting.

Ink doesn't wash out of paper. If you were to wash it out, the paper would end up falling apart.

wash the entire garment, by hand, in brake fluid, brushing ink stain to remove ink completely. Then wash in brake fluid cleaner. Then wash normally.

Wash it!