I'm a Demon King in Another World, and My Subordinate Is a Cat-Eared Girl

Concise version: Yu Yi and his cat were summoned to a different world, Yu Yi became the devil, and the cat turned into a cat-eared girl with super strong fighting power. ===== At the time of the decisive battle between humans and demons, the Demon King is about to be defeated. Yu Yi and the cat he was holding were summoned to a different world by the devil by accident. Demon King:! ?  Brave:! ? The three of them looked at each other, and the Demon King was suddenly horrified. What he was supposed to summon was a world-destroying beast, which meant that the taboo summoning failed and the price was backlash. The power of the Demon King was captured by the summoning array and transferred to Yu Yi, while the Demon King turned into a broken skeleton. Yu Yi becomes the new devil. The hero is hostile, but Yu Yi uses modern knowledge combined with magic to turn defeat into victory, and the hero escapes reluctantly. The steward of the Demon King's City suddenly appeared and met with Yu Yi, saying that brave men will gather forces to make a comeback, and the new Demon King must develop the Demon King's legion and increase its strength. Butler: "You can use the power of the Demon King to strengthen your subordinates and conquer more soldiers, Lord Demon King!" But his priority is his cat. How can a poor, helpless and weak cat survive in a dangerous alien world? Yu Yisui strengthened the cat with magic, and the cat turned into a girl Cat-eared girl: "I'm hungry, Yuyi~" Yu Yi: "...!" Vampires, night elves, Valkyries, fallen angels, dragons, martial arts masters, samurai... Ancient robots? They will all become Yu Yi's subordinates, strengthen the demon kingdom, and declare war on the despicable human kingdom.