Transmigrated to 1937: A Junior Military Intelligence Agent Unleashes S2

[Spy warfare + undercover agent + ruthless + sharp-minded + villain + no female lead] Lin Wanzhou, a high school student who was terrible at school, accidentally transmigrates back to 1937. With his foreknowledge and ruthless methods, he rises to prominence within the Military Statistics Bureau.

Director Dai: Wanzhou, could you be a little more discreet? The whole country knows you're undercover. What am I supposed to do?...

Lin Wanzhou: I can't be discreet at all. I want to expose myself and let everyone know I'm undercover. That's the only way to stay safe.

Military Statistics Bureau Chief: What kind of logic is that?

Lin Wanzhou: It's an open strategy. You country bumpkins wouldn't understand.

While undercover in the Military Statistics Bureau, Lin Wanzhou passes along a wealth of valuable intelligence. Later, when his power reaches its peak, he can even sway world politics. He brings forward the launch of S2, stirring up a storm across the Blue Star.

Feel free to read with your brains switched on...