Free gift with cream/serum purchase
Many reviewers received this mask as a bonus (おまけ) when buying Centellian24 cream or ampoule sets, which introduced them to the product and often converted them into paying repeat customers.
Brand loyalty to Centellian24/Madecassoside line
A large share of buyers already use and trust other Madeca products (cream, ampoule) and purchase the mask because they believe 'this brand never disappoints.'
Influencer and word-of-mouth recommendation
Several reviewers cite a YouTuber, Instagram influencer, or friend's recommendation ('人生シートマスク' claims) as the reason they first tried the product.
Sale/discount timing
Because the mask is considered expensive per sheet, many consumers explicitly wait for Olive Young sales or coupons to buy in bulk rather than paying full price.
Repurchase after proven results
A high number of reviews explicitly state this is their 2nd, 3rd, or 'countless' repeat purchase, driven by consistent hydration and brightening results.