Reborn in Another World with Two Bodies and a Sign-In System

The protagonist, Gongsun Yu, was called Chen Yu before he transmigrated. In his previous life, he had graduated from university. His parents both died when he was young, so his grandfather, Chen Ansheng, raised him. One day, while he was sleeping at home, his grandfather accidentally set the house on fire while smoking, and the protagonist died in the blaze. By chance, he bonded with a mysterious System and transmigrated to an unknown fantasy continent. The Desolate Heaven Continent, where the protagonist finds himself, is not as simple as it seems. The System he accidentally bonded with is called God-Level Sign-In 1.0. Before long, it will level up alongside the protagonist and bring him brand-new features: ascending to the Immortal Realm, entering the Demon Realm, and descending into the underworld. His first sign-in grants him another version of himself. Is he invincible from the start? But unknown challenges still await Gongsun Yu…