Back to High School: I Awakened a God-Tier Sign-in System

Jiang Yang's plane crashed, and he was reborn before his college entrance exams. His grades had already been terrible, but after all those years away, they were even worse. At that moment, he awakened a god-tier sign-in System. All he had to do was sign in to receive generous rewards. But his excitement lasted less than three minutes before he realized his System was kind of a scam. He came in last on an exam, and the System told him to brag shamelessly? He met his future wife, and the System told him to swear at her? He was punished with writing a self-criticism during the flag-raising ceremony, and the System told him to confess his love? His sign-in rewards kept getting more and more incredible, and just when he was finally ready to show off, the System actually told him to keep his little secret under wraps? Help! Was this System really sent by Heaven specifically to mess with him?!