Diary Girl is an electronic organizer pointing at teenage girls. After creating and customizing an avatar the player can use the features of the programme. The main function is the calendar system which can be filled with event reminders and diary entries. Using the touch screen keyboard each days allows entering up to 300 characters, setting a mood with a smiley face and noting the weather of the day.
Another feature is the built in chat function which allows chatting with other players over the Wi-Fi-Connection. The chat function consists of normal text chat and an audio component using the DS microphone.
To earn its spot on MobyGames Diary Girl offers a collection of minigames like matching and puzzle titles and a quiz game that is actually a personality test. Each game consists of three levels of difficulty.