That's right, the phrase came from video games—when you get enough life points you become invincible. But it was first used about 2008 by the originator of 2-chan. He meant it as the opposite of invincible (thus sarcastic/satirical) meaning people so alienated that nothing, no threat or punishment or even death can deter them from whatever evil deed might enter their demented imaginations. I think you said almost the same thing. There will be more of this but, for now, Japan is still an amazingly safe society. Even the US has been getting safer, with less violent crime since the late eighties when government agents were selling crack cocaine in poor areas. Those in power want us to be afraid because people living in fear are easier to control. School shootings are faked to control us. Racism is also wildly exaggerated or being created by people paid by Soros or others and manipulated by agents provocateurs. The world situation is not as bad as those in power want you to believe. Fight them by being happy and positive.