The Diary is an Android role-playing game developed by Yangyang Mobile. It is a spin-off of the horror visual novel, The Letter, and follows the childhood adventures of Rebecca Gales and Ashton Frey. The game has 16 diary entries, each requiring a key to access. A key is given for free each day. Once you've made a choice in the game, you can't change it, so choose wisely. The game has a cute art-style and over 100 colorful drawings. The Diary has garnered over 100,000 installs and has its own little fanbase.

The Diary has been updated with new entries. Season 2 and Epilogue have been added, and the German language has been added for Season 1, courtesy of Marcel Weyers. Various bug fixes have also been made. It is a free game but contains ads and in-app purchases.