I Became a Level 999 Mastermind Demon King

A child-soldier mage regains memories of a past life on the battlefield—and realizes this world is a novel with a doomed, apocalyptic ending. To avert it, the plan is simple: stick to the story’s “hero” and keep him alive. After some twists, the narrator sneaks into the duke’s household as the adopted youngest. One problem (actually three): the hero hates mages, the narrator is a deserter, and a messy mix-up has them living under a swapped-gender disguise. Now it’s constant tiptoeing to avoid being found out while plotting how to protect the hero… and somehow there’s always time for strawberry cake. A cozy, chaos-filled tale of a secretive “maknae” with a lot to hide.