If you restore skin's hydrating power,
it transforms into brighter, whiter skin. 
Conclusion about whiteness, based on skin physiology.

Areas with pigmentation (= dark spots and dullness*) are experiencing dryness. In these areas, the stratum corneum's barrier function has declined, leaving the inside of the skin vulnerable to inflammation, and that triggers melanin pigment to be produced in excess.
Basically, it turns out that the stratum corneum's "hydrating power" is what holds the key to whitening.

ACSEINE White Emulsion employs a new idea that works by restoring a stratum corneum that's become rough from dryness to a moist, supple condition. It keeps the stratum corneum healthy and leaves skin moist, clear, and bright, with no dark spots or dullness*.

*Dark spots and dullness are caused by sun exposure.
The above text is an explanation of the action mechanism of White Emulsion Cellup Gel W-CP (quasi-drug).