原子暗黒殿 / Genshi Ankokuden - The doll left behind
Chapter 1 - Stage 4
Combine the rainy weather(which reduces your movements by 1), the kedamas which have 3 lives and high attack power, the books when magic boosted by the fairies can become a powerful threat and you get your first decent challenge in this game.
Luckily, you don't have to kill them all. You just have to dispose of Shanghai and you clear the stage.