Will indigo dye my skin?

The answer is NO.

indigo soap in use

not in the soap form.

Distinctive color indigo has long been regarded for its deeply soothing and restorative benefits. During the Edo period, samurai wore a layer of indigo dyed cotton beneath the armor to help heal injuries faster because of indigo's antibacterial properties. In Japan, the color indigo often referred to as "blue of samurai".

The indigo dye permeates its essence long after fabrics become garments and is known to ward off mosquitos.