My Slayer System: Rise to Supremacy - Chapter 420: Crossover!

The extraordinaire has disrupted the silence of the world and ever since then, technology has taken a different path.

Overnight, young Ye Zhen suddenly discovered he had acquired a strange new ability!The meaningless cries of animals and insects in the mountains entering his ears began to sound quite different.“Quick, brother,” squeaked the mouse brothers, “the treasure in the back hill that can make us grow dozens of times in size is about to drop, let's go!”A swarm of mosquitoes buzzed, “Those two guys are here again, brothers, let's get them and have a feast!”A Cloud Winged Young Tiger faced Ye Zhen and let out one fearsome roar after another, “Mommy's not home, don't come any closer, come any closer and I'll eat you!”Everything changed because of this!

After getting betrayed and killed by the only person she’d loved, Miss Shang wakes up in the body of the cowardly crown prince Shang Wuxin, who, due to her own circumstances, was actually a girl cross-dressing as a boy. After inheriting the crown prince’s memories, Shang Wuxin has three things on her agenda:

1. Clean up the house

2. Gather loyal followers and soldiers

3. Get the throne

- Description from Novelupdates

After dying in an oddly anticlimactic vending machine accident, Kazuki Ren is reincarnated in the demon realm—not as a hero, not as a villain, but as the only human male student enrolled at the mysterious Academy of Ruin, a school where all the professors are demon lords and all the students are powerful, beautiful she-demons.Ren is told he has one task: survive.But there’s a catch. The Academy’s darkest secret is about to awaken, and Ren holds a hidden power that could either destroy the demon world... or rule it.Now surrounded by seductive demons with hidden motives, eldritch tomes, forbidden dungeons, and twisted exams, Ren must master his ability—or be consumed.Magic, mystery, danger, and temptation await in this dark academia harem fantasy.