Is It Really Reasonable to Make High Schoolers Punish the Wicked?

[If you had to choose between unlimited wealth and a one-of-a-kind System, or an ordinary school life, what would you choose?] Chen Jinmo had no choice. He was an utterly ordinary high school senior: excellent grades and a handsome face. On his eighteenth birthday, he was forcibly bound to the most troublesome System imaginable. From the day he was bound, it assigned him all kinds of missions every day: kill a rabid dog, break a thug's leg, kill an underground gang leader, kill the chairman of a multinational corporation! Later, it even sent him to kill powerful figures who could fly through the sky and burrow through the earth like immortals. At last, after a relentless stream of missions, something went wrong with his body. He stopped being himself. Beneath the blood-red night sky, the young man held an admission letter to a top university. Holy light that could heal the wounded shone from his left hand, while black mist that could devour life swirled around his right. In his mind, the System flashed warnings in a frenzy: [Warning! Warning! Warning! If your Goodness value falls below the critical threshold, your second personality will be activated permanently.] “So... my friend, the light in this world can't come from waiting. In the end, darkness must be devoured before light can be born.” [The protagonist is an adult, and this is a fictional world. Don't read too much into it!!!] [One heroine (the story may become heroine-free as the plot requires). No harem. The romance will be scaled back somewhat in the middle of the story. Nothing is off-limits, but the story's values are sound. Overall, it leans toward urban fantasy. Please read with caution if that's not your thing.]