Jennie

Jennie is a princess of the Emotions Kingdom.

Romi's cousin and heart-sister, a kind and innocent girl, she actually turns out to be the one who released all the Teeniepings since the beginning.

After revealing her true colors, she becomes the main antagonist of Alssongdalssong Catch! Tiniping, but then comes back to her senses and is given a second chance by everyone, allowing her to become nice again.

(Source: Catch! Teenieping Wiki)