KOUKYUU ICHIBAN NO AKUJO

Koukyuu Ichiban no Akujo summary:

The plain-faced Rinrei (Lin Li) can be transformed with makeup.
Normally, Rinrei is a simple and quiet girl, but when she wears makeup, even her heart is colored, and she becomes an immensely beautiful woman overflowing with self-confidence.
Her love of cosmetics is so strong that she has developed her own cosmetics that have become popular products in the capital.
However, her father, who is worried that she might miss her chance to get married due to her love for cosmetics, has her thrown into the imperial palace.
This is a unique and painful love fantasy set in the imperial harem!