Grogs Black Magic Ink is a special invisible ink that is totally invisible when applied but in turns into a deep dark color in reaction with daylight/UV-light

and mid-tone colors appear with more saturated energy than they would on white paper

rinse it under a tap

Rigolo and many more

uni posca pen case red Sabe Grogs Black Magic Ink isThis is an empty storage case shaped like an oversized POSCA marker, holding up to 12 standard medium markers (PC 5M size) or a larger mixed assortment of finer pens, pencils, and rulers. A secure zip closure wraps around the top to keep everything from spilling out in transit, and the case fits inside a backpack or tote without taking up much space. Specifications Capacity: up to 12 PC 5M markers, or a larger mixed assortment Dimensions: 20. 0 cm