Ankoku Kishi Monogatari ~Yuusha wo Taosu Tameni Maou ni Shoukansaremashita~ - Chapter 3: [The Reason to Fight]

Ye Xiao was a superior cultivator in his previous life. The three factions of the realm kill millions of people every time they attempt to seize cultivation resources. Wealthy towns turn to wastelands in just a single night. They cover up their crime with an assertion that the towns were suffering from pestilence and disasters.

They forcibly hold all the resources for cultivation, monopolize all valuable practice materials, and keep outsiders from cultivating so that only their three factions could cultivate in the realm. Ye Xiao declared war against the three factions in retaliation for their actions. He fought alone and ended up dying in vain. However, he is reborn into the mortal body of a 16-year-old boy. He will use the powers he cultivated in his last life and slaughter his way back into the Realm. The story begins!

- Description from Novelupdates

[The false necromancer has insufficient soldiers and is being ostracized and hunted. ]

[The real necromancer, countless skeletons, become the overlord of one party. ]

After Wu Heng obtained the double portal, he discovered that the original world was full of zombies.

When a gangster’s plan fails, another plan to survive begins.

Wu Heng chose to become a ‘Necromancer’.

Is it not allowed to summon the undead from another world? In the last days, the entire planet is a source of soldiers.

Can’t survive in the zombie world? Then I will live in another world and learn skills.

From then on, an undead army equipped with modern weapons appeared in the world.

Natural disaster strikes, millions of skeletons.

Immortal Bone Dragon, King of the Undead.

(Double portal + necromancer + magic + fantasy world + undead natural disaster.)

- Description from novelbuddy

A 30-year-old NEET is reincarnated into the body of an otaku that choked to death on instant noodles. As he comes to grips with his new life, he realizes that this world is subtly different from Earth. The denizens of this world are far better looking, and this new world also possesses futuristic technology as well as mysterious Yin Yang masters!