Cute, wearable shade curation
Reviewers repeatedly say the 4-color combos have 'no throwaway shades' and are easy to commit to compared to larger 9-color palettes, driving impulse purchase.
Gift-with-purchase bundle value
Many buyers bought specifically because the set included a free mini brush or eyeshadow stick/pencil, describing it as 'a great deal' (お得なセット).
Sale/discount pricing on Olive Young
Numerous reviews mention buying during a sale or add-on discount promotion, with some noting prices as low as ~250 yen, which strongly influenced the purchase decision.
Repurchase across colorways
A large share of reviewers say they previously bought another shade and liked it enough to buy again in a different color (色違いで購入).
Influencer/personal-color recommendations
Several reviews cite YouTubers, Instagram influencers, or a favorite Korean model/idol using the palette, and buyers matching it to their 'warm/cool tone' (이엘, 웜톤/쿨톤, イエベ/ブルベ) personal color type.