This paper proposes a system to automatically generate charts with fine-tuned difficulty levels: Dance Dance Gradation (DDG). The system learns the relationships between difficulty levels as training data. The difficult chart automatically would be adapted to easier charts through the learned model. As mixing multiple difficulty levels for the training data, the generated charts should have each characteristic of difficulty level. The user can obtain the charts with intermediate difficulty level between two different levels. Through the objective evaluation and the discussions for the output results, it was suggested that the proposed system generated the charts with each characteristics of the difficulty level in the training dataset.