Attack On Titan -shingeki No Kyojin- Complete -... Link

The "useful" lesson here is psychological. We all build internal Walls—comfort zones, denial systems, prejudices—to protect ourselves from painful realities. We tell ourselves, “I’m fine,” or “They are the enemy,” or “This is just how the world works.” But as the Colossal Titan kicked a hole in Wall Maria, it revealed a brutal fact:

Eren Yeager, the hero who wanted to kill all Titans, became the monster he swore to destroy. He unleashed the Rumbling—millions of Wall Titans marching to flatten the entire world outside Paradis. His logic was horrifyingly simple: “To protect my home, I will destroy every other home.” Attack on Titan -Shingeki no Kyojin- Complete -...

For years, the people of Paradis fought with righteous fury. They believed Titans were mindless monsters. Then came the gut-wrenching reveal: Titans were once human—specifically, their own people from a lost faction, turned into weapons by the mainland nation of Marley. The "useful" lesson here is psychological

Don’t become the Titan. Become the one who says, “He is not my enemy. He is also trapped.” He unleashed the Rumbling—millions of Wall Titans marching

Young Eren Yeager lived in a world of comfortable lies. The people of Paradis Island believed they were the last remnants of humanity, caged inside three enormous Walls—Maria, Rose, and Sheena. They called the man-eating Titans outside a natural disaster.

But the wise Commander Erwin Smith knew a secret: