The caverns boast a vast array of bizarre creatures, most either infected or determined to kill any intruders.
"Tiny squib... You approach fearless. Are you a hunter like me? Do you feel the urge inside, to stalk, to kill, to understand?
Then take it! My journal. It will aid you. At first the text may seem difficult to discern, but a learned hunter will come to understand its words. Venture the depths of this land and slay its beasts. Prove yourself worthy to bear the mark of Hunter."
The Hunter's Journal is a compendium of every enemy found in Hollow Knight, given to the player by The Hunter. Defeat enemies to add new entries to the journal. Defeat a specified amount of each enemy to unlock additional notes from the Hunter about that enemy, as well as bits of lore, techniques for fighting said enemy, or even information about the Hunter himself.
The mark of a true Hunter.
I have no offspring, nor subjects, nor worshipers. The sum of my being, my learning, my instincts...I leave it all to you. Good luck, Hunter.
Granted to the player by talking to The Hunter after completing every entry in the Hunter's Journal.
Unlocks the True Hunter achievement.