Hero Analysis for the Future

Hero Analysis for the Future is a personal belonging of Izuku Midoriya.

Overview
Izuku uses this notebook to jot down his own analysis of Heroes and their Quirks, after observing them in action. The contents of the book are apparently very detailed and well-written, impressing even All Might. Izuku also uses this book to write down ideas for his own hero career, such as Costumes and potential Super Moves.

Izuku treasures this notebook, as it contains several years worth of observations about Heroes that he admires. At the beginning of the series, Katsuki Bakugo stole, burned and then tossed this notebook away in front of Izuku, who had managed to retrieve it later. All Might also signed an autograph on this notebook, after saving Izuku from the Sludge Villain.

It's implied that Izuku has multiple notebooks, as the one used at the start of the series had a numerical identification (in this case, "No. 13").

Trivia

 * The notebook appears to have a brand, "Campus" (changed to "Campos" in the anime).