Infinite Dendrogram (2020)

In 2043, the world's most advanced VRMMO video game is created. The game engages all five senses and uses lifelike NPCs. Reiji Mukudori joins this immersive world and allies himself with his brother, Shuu. But Reiji discovers unlike his own in-game character, when his NPC brethren die, they're gone forever. And to top it off, a war is coming.