After my sister was killed, I summoned Gundam to bomb the world

In the apocalyptic wasteland, strange beasts are rampant, making human society cruel and hierarchical.
Lin Yan awakened his summoner talent, which was generally recognized as useless, and became a dustman.
But as a time traveler, he awakened the golden finger that can summon technological weapons, from Gatling to Armor Hero Summoner, and even Gundam and Two-Dimensional Foil.
He returned home with anticipation and joy, but he only saw his sister, who depended on him for everything, lying in a pool of blood.
Looking at his dying sister with broken bones all over her body, Lin Yan knew that it was time for this world to change...