I Became the Savior

My mission is to destroy civilization on earth. However, the plot reversed the moment I returned to Earth from a distant galaxy. Because the system I was bound to was compromised, my mission changed. I, an ordinary high school student, not only did not carry out the mission of destroying the earth, but I went to ancient times to be the savior.

In an era without any advanced technology, what kind of weapons should be developed to fight against the invasion of alien colonists? It's so hard for me...

My mission is to destroy civilization on earth. However, the plot reversed the moment I returned to Earth from a distant galaxy. Because the system I was bound to was compromised, my mission changed. I, an ordinary high school student, not only did not carry out the mission of destroying the earth, but I went to ancient times to be the savior.

My mission is to destroy civilization on earth. However, the plot reversed the moment I returned to Earth from a distant galaxy. Because the system I was bound to was compromised, my mission changed. I, an ordinary high school student, not only did not carry out the mission of destroying the earth, but I went to ancient times to be the savior. In an era without any advanced technology, what kind of weapons should be developed to fight against the invasion of alien colonists? It's so hard for me...