Yachiru-san wa Homeru to Nobiru

Yachiru is a Hasshakusama youkai living in the human world. Because the prevailing public image of Hasshakusama is that they're lewd (not scary), her powers have weakened and her height has shrunk from its original 8 shaku (240 cm) to about 190 cm. She strives to correct that impression, but each day is another failure. However, while at the cinema to study horror films, she meets Seiichirou, a young man who is a huge fan of Hasshakusama. That's when Yachiru realizes that whenever Seiichirou praises her, her height returns to its original size...!!!

(Source: Kodansha, translated)