Should anti-aliasing be turned on for Ouka 2?

No.

Anti-aliasing is to reduce the jagged pixels on the edges of game graphics, making the picture look more detailed instead of a full-screen mosaic. The larger the value, the better the picture. Also translated as edge softening, aliasing elimination, lossy anti-image folding, etc. Multisampled anti-aliasing is a special type of super-sampled anti-aliasing (SSAA). MSAA first comes from OpenGL. Specifically, MSAA only performs super-sampling anti-aliasing processing on the data in the Z-Buffer and Stencil Buffer.