Create a highly detailed industrial design concept sketch on an off-white lined notebook page featuring a Nestlé KitKat chocolate bar as the main subject. The page should resemble a real product designer's brainstorming notebook with a large three-quarter perspective hand-drawn illustration of a partially unwrapped KitKat bar. The wrapper is bright red with the classic white KitKat logo, while the exposed chocolate fingers reveal realistic crunchy wafer layers, including one broken piece with visible crispy wafer texture and scattered chocolate crumbs. Render the sketch using black ballpoint pen linework, fine cross-hatching, architectural perspective lines, and red marker accents that match the KitKat packaging. Add handwritten annotations, arrows, and design callouts pointing to features such as "Crunchy Wafer Texture," "Classic Red Wrapper," "Chocolate Coating," "Easy Tear Opening," "Signature Logo Placement," "Wafer Cross Section," and "Break Here." Include tiny doodle illustrations of a person enjoying a KitKat with a cup of coffee, playful sketch icons, rough concept thumbnails, engineering notes, and packaging design variations scattered naturally across the page. Place a small reference image of the actual KitKat bar in the lower-left corner with a bold blue arrow pointing toward the main concept sketch, indicating the design study reference. Add subtle coffee stains, pencil guidelines, erased construction marks, folded paper corners, light ink smudges, notebook punch holes, and realistic paper texture to make it feel like an authentic designer's notebook. At the top, write a handwritten title: "Character – Product Study 01", with Nestlé KitKat logos sketched in the corners. Premium industrial design sketchbook aesthetic, realistic pen and marker rendering, product concept art, clean composition, ultra-detailed, high-resolution, professional design presentation, 8K.