Descent of the Demon God한중월야

and arrived at the world 1000 years from his time, the world obviously more advanced than his time but the power of martial artists has regressed for some reason, so he never has to use full power to deal with them and the technology also didn't reach the point where it's possible for time travel, there's also the gate which monsters would come out, as MC trying to get used to the foreign world, he found out that world is continuing from where he's gone missing and the sky demon order has dissolved over 20 years ago because of an unfortunate incident and the remnants of the order is fighting among themselves, making it impossible to rebuilt the order, MC then taking extreme measure to unite the people, punish his descendants based on their sins and regains the glory of the order,

between those he also found out that the descendant who gave him the nano machine gave up on returning to the future and send 3 mc's people holding the code to the location of time machine with hibernation (i teared a bit when MC got angry cause the time machine can only be used by 1 person, that means his people has to stay there), but some mysterious group is interfering with it (disturbing the hibernation), MC saw the recording of his descendant trying to make a time machine although he already take measures to send available device to MC, he unable to complete it in his time so he trying to create A.I by transfering his knowledge to a supercomputer (MC feeling bad after he saw the recording of his descendant crying in pain because he's nearing death, I cried too), but something wrong must has happened as that A.I suspected to be in the hands of that mysterious group,

Among those problem, the creatures from the gates also become issue (mtl gives various name to these creatures, devil, demon, the horsemen (like the 4 horsemen of apocalypse), MC found out those creatures who look similiar to humans has been infiltrating human society to search for specific treasures which is necessary to ascend the empty throne in their world, MC happened to hold some of the treasures, after the battle with the current king who suddenly showed up after leaving the throne empty for a long time, MC found the truth in the dead memories that the current king has dissatisfaction with the former king about humans, the former king fond of humans while the current king think of them as livestock, as the former king injured in a fierce battle with other race leader, the current king take advantage of that and throw the former king into the gate of earth hoping he would be destroyed in gate travel or die among humans he likes, some time later the current king curious about the former king and decide to confirm his death, but when he arrives at the earth he saw the former king still alive and adapted being human, MC see the shocking truth that the former king of demon is his ancestor the founder of sky demon order, the ancestor beat the current king until almost dead and kicked him back to their original world,

As the conflict with the demon creatures from beyond the gates solved, MC informed by them that the gates opened everywhere on earth is caused by damaged planet defense core, it's caused by the long standing enemies of the demons (from what I understand about their description, with white wings and such, obviously angel clan) they intended to take over the earth but something odd as the earth is not invaded, MC decide to wipe out the enemies who causing disturbance on earth and repair the damaged planet core, while the mysterious group is up to something creepy again, what would you expect with bio-criminal company who use their advanced knowledge to clone human, make genetically enhanced human (even 1 of mc's people kidnapped in his hibernation and wake up with modified body), creating nanobomb to control and kill people etc.)

MC eventually found the truth about the mysterious group, the descendant who created A.I is betrayed by someone who helps him, that traitor made the A.I fully free from human control and they ended up killing the descendant who already suffered from illness, but the greedy traitor wanted all advanced knowledge and decide to extract it from the descendant's brain, fortunately they failed, they has a purpose to create a god using the A.I, with angel clans involvement they create a vessel for the angel's leader (maybe his body injured badly like the former demon king in their fight), the thing with combination of persona of A.I and angel's leader then show up bringing chaos to the world, it's a being of destruction, even MC has a hard time fighting it, this is a rare time when he seem humanely as he reveal his feelings that he didn't want to go to a new world, he didn't mind not getting stronger if he can return to his original place and then his ancestor (soul?) help him destroy the enemy,

MC then found the room with his descendant's brain, among the thing he used to own, there's code for MC saying 'where our relationship began', MC realise the location of the time machine and go pick it at the place he first met his descendant, founding it means the permanent separation from this world timeline and he can't bring anyone back, they have emotional goodbye, MC told them to take care of the order, half of the planet core has been repaired, the gates stopped appearing on some continent, MC told them to cooperate with the demon clan to repair the rest of it, MC returned to his time and only 3 days has passed since he goes missing although he has spent a few months on that other timeline, he already emotional from separation with the future people, when he saw his lover again and others face overlap with his people that got leave behind, he teared and hug his lover for a while