Alien Invasion, but I Started Invincible!

Alien worlds have arrived, countless to the Silicon-based Federation world. The Demonic Insect World is raging on the earth, and this time he desperately defended human civilization. In the end, he was assassinated by a surrenderer to the Silicon-based Federation. But the jade pendant he found from ancient ruins helped him return to the day before his birth in another world. In this life, he did nothing because he started with full strength. He no longer relies on anyone, and he no longer protects anyone. He is the god of death who is feared by the demon world. He is the rebuilt electric mosquito swatter, the messenger of death, and the god of death. But is he really at fault?