Nakama ni Uragirare Shokei sareta Necromancer, Undead-ka shiteita Eiyuu 10000-nin wo Sosei shi Saikyou no Oukoku wo Tsukuri Fukushuu wo Kaishi suru: Anei no Gyokuza ni Eirei wo Tsudou

Crow, a necromancer, gets betrayed by his comrades and cast into the Abyss. But, consuming the miasma, he rises again, fully resurrects 10,000 heroic spirits who had once been destroyed, and founds the mightiest of kingdoms.

With a legion of ancient warriors at his command, Crow exacts a gruesome and relentless revenge against the former comrades who betrayed him and the god who was behind it all...!

(Source: Kodansha, translated)