pyaino is a deep learning framework designed for practical AI development, while keeping the power of NumPy directly accessible. It provides automatic differentiation in a define-by-run manner, and adopts the same matrix multiplication convention as mathematics, avoiding confusion for users familiar with numerical computation or mathematical notation. A distinctive feature is that higher-order derivatives are computed mathematically exactly — for example, the second derivative of a linear function correctly evaluates to zero, something many frameworks fail to guarantee. In addition, pyaino offers ready-to-use modules for tasks such as image and language processing, allowing you to build machine learning or deep learning models with just a few lines of code. Each module explicitly defines both forward and backward propagation, so no unnecessary computation graphs are generated, making resource usage efficient and model behavior easier to verify.