Tree of Aeons - Moving house

A novel revolving around being transported to another world with an op system. The mc spends his day chasing skirts and doing missions to level up. A standard journey to the top with lots of girls from various animes and games with a twist of that gaming feel (hunting mobs, doing missions).

- Description from novelupdates

…but it seems pretty doable.

Years ago, Earth was indoctrinated into the “System.”Earth was not the only place with the System, however. With the System came the other races, Invaders. The Invaders had one goal, to obtain ownership of this new habitable planet. This created a bloodbath, and for years the war raged.This didn't really have much to do with Derek. Derek was kind of a loner. Yeah, he enjoyed the occasional chat or drink with others, but he never stayed in one place too long or really got to know anybody new.Derek did happen to be rather strong. After the years of fighting monster and Invaders alone, he had become quite adept at surviving. One thing that helped keep him alive was his refusal to get involved with others. He rarely cooperated with teams.One day, Derek broke his rules and decided to lend some help, as the mission didn't seem too hard. He should have stuck to being alone.

Doomsday crisis, zombies are attacking, the situation is critical.Don't let our enemies change from zombies coming at us to humans we protect behind us.“Brother, what would you do if I turned into an irredeemable zombie?”“…kill you.”“Then do you know what I would do if you turned into a zombie?”“Kill me.”“No,” he lifted her long hair, revealing her smooth neck.“You are crazy. I advise you to give up this irrational idea.”“Brother, this world has gone crazy.”