Transmigration? Step Outside and You're in Another World

I transmigrated, but something seemed a little unusual. Lu Ren had just been about to go out and buy some KFC when he saw a princess asleep on a bed inside a prison cell. He fell into deep thought. Then, almost unconsciously, he shut the door. After a few seconds of silence, he opened it again. Now he was staring at the First Demon and the strongest swordsman facing off, his gaze a little vacant. So he quietly shut the door once more, smiled, and slapped himself a few times to wake up. Only then did he slowly open his front door again, meeting the gaze of the Demon Lord Milim, who happened to be passing by. "..." At that moment, the light finally vanished completely from Lu Ren's eyes. Looking down at the doorknob he was gripping, he couldn't help but feel utterly lost about life. He just couldn't figure it out: "How the hell did I manage this?"