MTL - The Five-year-old Milk of the Xuanmen Group’s Favorite Boss - Chapter 436 I will be nice to you in the future!

Amid the steam of the industrial revolution, mysteries surge beneath the surface. Cults and secret societies seek the extraordinary in the shadows, while hidden gods gaze upon humanity from the heavens.Forbidden knowledge, sacrificial rituals, and forgotten histories—mystery is everywhere.Dorothy, unexpectedly transported to this increasingly bizarre world, discovers that to survive and move forward, she must adhere to one principle:Knowledge is power.And forbidden knowledge?That’s an even greater power!

What happens when a fanfic author with a habit of lying and scheming suddenly finds himself as a self insert during Duelist Kingdom? What happens when you have Yugi, Joey, Kaiba, and the rest encounter someone who knows all about every major player in their saga... and sees no problem with abusing said knowledge? Chaos, dear reader. Sweet, sweet chaos

This novel is also known as Only I Level Up

10 years ago, after “the Gate” that connected the real world with the monster world opened, some of the ordinary, everyday people received the power to hunt monsters within the Gate. They are known as “Hunters”.

However, not all Hunters are powerful. My name is Sung Jin-Woo, an E-rank Hunter. I’m someone who has to risk his life in the lowliest of catacombs, the “World’s Weakest”.

Having no skills whatsoever to display, I barely earned the required money by fighting in low-leveled catacombs… at least until I found a hidden catacomb with the hardest difficulty within the D-rank catacombs!

In the end, as I was accepting death, I suddenly received a strange power, a quest log that only I could see, a secret to leveling up that only I know about! If I trained in accordance with my quests and hunted monsters, my level would rise.

Changing from the weakest Hunter to the strongest S-rank Hunter!

- Description from Novelupdates

What would you say is the most valuable thing in this world?