I used to be a jobless shut-in, with no money and no girlfriend.
Then I accidentally transmigrated to the world of Naruto and activated the most ruthless System in history:
Watching Uchiha Itachi slaughter his entire clan: +100 Cruelty Points.
Watching Jiraiya get killed by the Six Paths of Pain: +60 Ruthlessness Points.
Cruelty Points can be exchanged for chakra.
Ruthlessness Points can be exchanged for ninjutsu.
On top of that, completing Hidden Missions can earn rewards like kekkei genkai, the Sharingan, the Rinnegan, and more.