Game Invasion: Awakening the Necromancer at the Start

Having crossed into a world invaded by a game, Su Wan awakens as a necromancer.
While others summon 1 skeleton, he summons 100.
It takes others 3 days to level up, but he reaches the maximum level in 1 hour.
When he flooded the abyssal demon tide with a sea of ​​skeletons,
The world was shocked.
What's even more shocking is that his sister—an SSS-class Eternal Seraph—is a yandere brother-obsessed woman.
"My brother is mine, and any woman who gets close to him will die."
The school beauty confessed her love? She teleported me to the Arctic.
A Valkyrie challenge? She beat me so badly I had to call her "sister."
The Elf Queen wanted a marriage alliance? She blasted him off Earth with her holy light.
Until nine stunningly beautiful women stood behind Su Wan:
Iceberg Swordswoman, Berserker Mature Woman, Mecha Girl, Nine-Tailed Fox, Demon Princess...
The younger sister smiled: "Okay, brother can have a harem—"
"But I must be the rightful wife!"
Su Wan: "Um...can I speak?"