Quickly Wear and Fight Monsters

(There are brain palace battles, time travel, systems, fandom, unlimited streaming, and cross-era) Xiao 0 was obsessed with "Deep Palace Song", and after accidentally traveling through time, he actually came to the world of "Deep Palace Song" to start an unlimited stream of harem battles. In the end, who is inferior to one person or superior to ten thousand people? Or is it that humans are the swordsmen and I am the fish and meat? Let's take a look at the protagonist group. They are working hard at every step and using all their mechanisms. What avenue will they create in order to survive?