Capturing the character's unique design in a demon slayer drawing requires a few key considerations. Firstly, take the time to study the character's appearance carefully, paying attention to their distinctive features such as their hairstyle, outfit, and weapon. Secondly, focus on the proportions of the character's body, paying close attention to their height and build. The demon slayer character designs tend to be highly stylized, so it's important to capture these unique features in your drawing. Thirdly, think about the character's personality and try to convey this through their expression and posture. Finally, don't be afraid to put your spin on the character's design, adding your personal touches while staying true to the overall look and feel of the character.