Transmigrated into another world as one of its most dangerous professions: the Demon Lord.
To survive in another world, one must be more cautious than the average person.
Every race and monster has its own weaknesses. Learn them carefully, and you can stand undefeated.
Take slimes, for example. They usually have a soft core inside them. As long as the core remains intact, their bodies can regenerate endlessly. The core is their most vulnerable and sensitive spot. Grab it and rub it repeatedly, and they will instantly lose the ability to fight, making them much easier to deal with.
Then there are dragons. The base of their wings and their underbellies are their greatest weaknesses. Strike and rub them repeatedly with just the right amount of force, and they will lose the ability to move, unable to fly or fight.
And then there are elves. Though they look human, their pointed ears and legs are also fatal weak spots. Rub them gently, and they will let out a "pitiful" cry, their eyes going vacant as they slump to the ground, completely defenseless.
Demon Lord: I've learned all these monsters' weaknesses, but for some reason my kidneys have been getting worse lately. Does that mean I'm still not being cautious enough?
(P.S. This is a silly, lighthearted comedy with no angst, but it may challenge your values, so read with care.)