Kobayashi-san Chi no Maid Dragon – 13 (END)

「終焉帝、来る! (気がつけば最終回です)」 (Shuuentei, Kuru! (Kigatsukeba Saishuukaidesu))
“Emperor of Demise Arrives! (It Was the Final Episode Before We Knew It)”

I’m pretty sure that’s not what happened in the source material — but I still loved every moment of it.