It is a subtle shift—a chest rising, a shoulder swaying—driven by nothing but a sine wave and a spring calculation. The eyes, which were just flat pixels a moment ago, now track your mouse. They are not alive, of course. It is just math: (mouseX - centerX) * 0.05 . But it feels like attention.
When the VTuber laughs, you see the throat deform. When the game character sighs, the shoulders fall on a cubic bezier curve. There is no physics engine in the real world; there is only the illusion of weight. live2d cubism
They call it "Cubism" because it fractures reality. You learn to love the seams. You learn that a perfect head turn requires you to hide the back ear at exactly 3.2 degrees. You learn that "breathing" is just a sine wave on the Y-axis. It is a subtle shift—a chest rising, a