Rohto Hada Labo Shirojyun Series is their flagship lotion range. The premium version of Shirojun "Shirojun Pemium" contains what is called W-Tranexamic Acid, which is thought to suppress the generation of melanin and may prevent mottled and freckled skin.
Tranexamic Acid also may protect your skin from UV damage.
Repeating users of this product might want to check the eco refill: