Are F-Class Ninjas Weak? Reiki Instantly Kills an S-Class Spirit Beast

[I can't think of a better title, readers who have better ideas please send me a private message] Xinghe, who was playing games in class, traveled to another world and became a waste. Xinghe got the system and used Raiki to kill the biggest boss instantly. What will happen next... [My wife is still a student and can only update on weekends]