U's Diary (Ｕの手帳, U no Techō) is a key item held by Yew Geneolgia in Bravely Second: End Layer. Just like D's Journal, it houses important information on monsters and items he and his party come across. It also contains an event viewer and help manual.
Main Article: Bestiary (Bravely Second)
Yew keeps detailed notes on the creatures he and the other warriors encounter. By defeating the same enemy several times, Yew can learn and write more pages with all sorts of trivia and useful information. The characters can also be seen jotting down their comments and opinions about each monster.
Related ThreadsVera's BD Diary - last post by @ Oct 28, 2014
Yew's Diary - Guides Index - last post by @ Apr 18, 2016