Unfortunately, I couldn't find any specific information on an uncompleted art book by Takeshi Obata that is available in PDF format. However, I can suggest a few options to help you:

For artists and aspiring creators, the art book is an invaluable resource. Obata's work is renowned for its attention to detail, and the book provides a wealth of information on his techniques, from sketching and coloring to composition and storytelling. By studying Obata's approach, artists can gain a deeper understanding of the craft and refine their own skills.

Unlike standard art books that simply reprint cover art, Never Complete —the title deliberately hints at Obata’s relentless perfectionism—is a 200+ page hardcover behemoth. It was published at the peak of the Death Note mania (around volume 11 of the manga).