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Tear Jerker: GunBuster
GunBuster's final episode - "Welcome Home". It never fails to make this troper cry. When our heroines go down into the Black Hole Bomb to activate it manually, Jung, their last remaining friend, promises to give them a big welcome home when they get back. But they're in the center of the galaxy, and with Time Dilation in full effect, they don't make it back to earth until 12,000 years later, only to be greeted by a dark, silent Earth. But as they're thinking that they are the last humans left... the entire planet lights up in a continent sized "Welcome Back" sign. Jung kept her promise.
And of course, the corresponding scene from the opposite side in the sequel Diebuster, bringing the epic full circle.