Report

Journals are recurring mechanisms in the Kingdom Hearts series. While Kingdom Hearts, Kingdom Hearts II and Kingdom Hearts Chain of Memories (not including Reverse/Rebirth), has Jiminy's Journal, Kingdom Hearts Birth by Sleep, Reverse/Rebirth, Kingdom Hearts 358/2 Days and Kingdom Hearts Re:coded has various different books in which data, about different characters, enemies and encounters and more, is recorded.

Kingdom Hearts Birth by Sleep
Aqua, Ventus and Terra hold their own individual Journals to record events. The Trinity Archives holds additional data covering all three stories.

Reverse/Rebirth
Riku uses the D-Reports (D standing for Darkness) to record data.

Kingdom Hearts 358/2 Days
In 358/2 Days, there is much less data recording, with only Roxas' Diary covering events along with the Secret Reports and the Enemy Files detailing enemies.

Kingdom Hearts Re:coded
The Debug Reports acts as the Journal for Re:coded. It contains five sections with a percentage representing how much that section is completed (although 'Trophies' has a number out of 30).
 * Trophies: shows achieved trophies and progress to achieving trophies.
 * Collection: shows all Commands, Keyblades and Accessories.
 * Story: summarises the events in each World.
 * Enemy Profiles: shows details for all enemies, including descriptions, drops and how many times an enemy has been defeated.
 * Character Files: contains short biographies for each character.