War of Resistance: From the Start, One Old Rifle, One Shot Per Invader

[War of Resistance + transmigration + System + sniping + fighting the Japanese invaders + ruthless decisiveness + rising behind enemy lines] Modern sniper instructor Shen Qingshan opens his eyes in 1937, having transmigrated into the body of the notorious good-for-nothing young master of Lutougou. From the start, the train is stopped by the Japanese invaders. Wounded soldiers, civilians, and female students are all aboard. Outside, machine guns are set up, while a traitor leads the enemy in searching the train. Everyone else is trembling with fear. All Shen has is a battered old rifle and three bullets. Fortunately, the shooting range in his mind has come with him, and he can master every skill a sniper needs, from steadying his aim and gauging distance to reading the wind, finding cover, and baiting the enemy into firing. Starting with a single shot that blows away a Japanese machine gunner, Shen Qingshan seizes weapons, rescues people, kills traitors, and takes down blockhouses. He rises from a young master in the local security force to the commander of a sniper squad so feared that the Japanese invaders dare not even lift their heads at night. The Japanese have a blockhouse? Take it down. A traitor dares to lead the way? Kill him. The enemy sends in a sniper? Then it's sniper against sniper. Let's see who dies first!