Thank you very much for stopping by my friend, I appreciate your comment. And well, the program I use is called Paint Tool Sai, and it has different tools for drawing, from brushes to pencils and lines.

In my case, I usually use the curved and straight lines to clean my rustic sketches. I work with them to make the final lineart of each of the objects or characters that are in my drawing. I feel they give them a more professional finish. Best regards!