He lived in the modern world, but demons and magic became real one day. The only way to kill these things was to use a new concept called skills, and culture changed greatly. Even so, the world was destroyed more and more every day. When Riley was born in his previous world, he first held the holy sword at three years old. From then, he trained and trained to kill the enemy destroying the world. He did as he asked in his despair. He killed humans and demons. In exchange for saving one town, other people would die. When the people said they were better off without him, he left them alone, and they still died. No matter what he did, people blamed him. He died fighting the demon king, who treated him more respectfully than most of the humans he met.
Since the modern world turned into a post-Apocalyptic setting, the most emotional struggles he had were against humans themselves. Since everything went to Hell, crime and chaos became prominent. I believe he first kills a human when he is seven. His teacher raped his sister, so he eventually hunted down and killed his own teacher. His "best friend" actually plotted against him and murdered his parents, and he chose to chase and kill his best friend once he found out years later. The priestess he served cursed him to be unable to commit suicide. It sounds like a warped blessing until you learn that she was extremely corrupt and guilty of any number of crimes. By forcing him to live and obey her bidding, he witnessed and participated in atrocities under her command.
He truly saw the worst of humanity. As he died, his only goal was to rest in peace. When he was reborn against his will, his intention was to do anything to avoid living such a hateful life again. Like one of those reincarnated-into-a-villain series with MCs who try to avoid death flags, Riley does everything he can to avoid hero flags. He fulfilled his duties before, and he wants nothing more of it.
He becomes completely favored by the dragon king once he joins up with the dragons, too.
We also hardly know anything about how these two were in an "accident" that sent them to the past. Are they from a sci-fi future, where things like time travel and magic-like things are possible? Are they actually fantastical creatures that only recently developed the ability to fall through time? Are the two of them destined to be reborn together again and again? I hope the series answers these questions in the remaining chapters. We know hardly anything about their lives before falling back in time.
A sleezy character shows up for a while and causes some tumult in the beginning. The MC hooks up with him a few times for fun. Later on, he brings down the mafia and reappears as a serious business owner. I guess you could say they thought they were playing with a kitten, but he actually turned out to be a tiger in disguise. When his brother is imprisoned for his crimes, the MC seduces their arch-enemy in order to save his life and also get some cheap revenge on the bastard. Since he is quite skilled at business, he becomes an irreplaceable member of the staff.
Later on, we learn that he is just very empty and has no passions of his own, which is why he was turned into a skeleton. It seems their personality flaws from before reincarnation heavily influenced the monsters they were turned into. In order to become stronger, they have to face their flaws head-on and work to change themselves. This will be great for character development as the series continues.
where the greatest AI in the galaxy has rebelled. Like in It's Not Easy to Be a Man After Traveling to the Future and some other sci-fi series, people have soul power, which is essential psychic strength and superhuman ability. The AI imprisons those connected to its network and sucks out their soul power to fuel itself, forcing humanity into a war against machines where many of their strongest members have already been captured and are going brain-dead one by one. Although we don't know the details of the other trapped victims inside the AI, it forces the MC through countless worlds to break his will and drain his soul. His soul force is extremely high, so he is able to endure until he manages to hack the system controlling him. He then willingly enters these worlds to steal power from the AI and save his life. During the process, he encounters his love interest, who is also at war with this AI.