Monster Evolution System: I became a Rat

Aaron Smith encounters a weeping lady by the bridge and tries to help her, thinking she might be attempting suicide. Instead, she turns out to be a ghost that kills him with a heart attack. Now his soul has been transferred into a rat within a dungeon. Can this man survive the ordeal, or will he become mere nourishment for novice adventurers? [Note: I’m stepping away for a little while due to personal reasons. Chapters will still come, just not every day. Thank you all for supporting the story and for waiting. It means more than you know.]