birth by sleep is about 10 years before sora, riku ,and kairi and three youths control the keyblade and hunt for their master and prove they can be better at things then they suspect and they have to battle master xehornort and his apprentice and fight for thier lives.
10 years before the events of kingdom hearts. It is revealed that Ventus is the first keyblade wielder before Sora.The new three main characters: Ventus, Aqua and Terra.
Yes! It's set 10 years before Sora got the keyblade. The three main characters are Ventus, Terra and Aqua!
Also, some of Organization XIII's Somebodies are in it! Like Even (Vexen), Zexion (Ienzo), Braig (Xigbar), Dilan (Xaldin), Isa (Saix) and LEA!!! (MY Любовь AXEL!!!) There are a few more... But Ты know, just to keep this short I only named a few.