Time Travel: National Body Training

Ten years of Blue Star Defense War, Star Mites have proven to mankind that any civilization that relies on external objects to arm itself without developing its own strength will eventually be destined to be destroyed. The mechanical industry that mankind is proud of collapsed in ten years of confrontation and became unsustainable. Humanity in this time and space became extinct. Jingnan, who accidentally traveled through the time tunnel and returned to the past, wanted to shoulder the heavy responsibility and turn the tide, but was unexpectedly intercepted by his senior... Humanity has begun an era of physical training for all!