"古文単語のたまご" is an iPhone application designed for studying classical Japanese vocabulary. The app offers smooth performance and includes a review feature to enhance study efficiency. Users can solve numerous problems, with incorrect answers being recorded and displayed at the top for easy reference. Additionally, a feature to solve only the previously incorrect questions is available. Study sessions can be conducted in a random order for better retention. Even after returning to the home screen, users can seamlessly continue where they left off. The app also provides a clear indication of items that require review at the bottom, allowing users to manually adjust the settings for efficient learning.