The application '한자 사자성어' is an educational tool designed for learning Hanja and four-character idioms in a structured manner. It offers a vast database of 4,069 Hanja characters, categorized from levels 8 to 1, along with 600 four-character idioms. Each Hanja character is supported by related vocabulary, similar meaning characters, and visually similar characters, enhancing the learning experience. The app also features a 'writing practice' function, allowing users to practice writing Hanja characters directly within the app.

To make learning engaging, '한자 사자성어' includes interactive quizzes that challenge users to find characters based on phonetics, fill in blanks with the correct Hanja in idioms, and match meanings to specific four-character idioms. Additionally, it provides a daily widget that delivers one Hanja character and one idiom, customizable by proficiency level, offering a consistent and manageable learning pace.