Description 
"What are you writing in there?" "Anything and everything."

Noboru spent some time in the Abyss. How long he can't ascertain. Time in the Abyss and on Teyvat seem to flow asynchronously as far as Noboru was able to tell. And in that time he logged everything he saw and experienced in a journal his mentor gave him shortly before he disappeared. There are rough maps and illustrations of strange landscapes and sculptures. There are notes intricately detailing various phenomena unique to the Abyss. Most of his notes pertain to the ley lines and their connection to the Abyss.

He had always been fascinated by the ley lines above ground. His mentor took him to many sites and domains where petrified trees grow. If there's one thing Noboru loved from his time in the Abyss was his chance to study the ley lines on the other side of the world. It's in the pages of this book that Noboru has chronicled details and accounts Sumeru scholars wish they could be privy to.

"These roots and branches... could they be from the very core of Irminsul?"

Noboru kept with him what little samples and trinkets he could from the Abyss, but he could only carry so much. So the rest he carried in his tome. Speculations and theories and hypotheses about the Abyss, its connection to Teyvat, and to Irminsul. The time in the Abyss changed the text. Some manner of Abyssal energy charged the pages and if one places their hand on the pages they can faintly feel the vibrations of an unknown energy emitting from them. The Abyss changes anything and everything that enters its chasms. Whether it be the nature of a person or the pages of a book.

Noboru keeps his book on him at all times. Besides his vision and his friends, it is one of the things he cherishes most in this world. If someone were to swipe the book out from under him, a terrible fate awaits them.