Normally, when you use a mechanical pencil, the lead wears down on the writing side first, so the lead gets progressively scratchier and sharper as
Uni Kuru Toga Mechanical Pencil, 0.5 mm, Black, Pipe Slide – St. Louis Art Supply
the kurutoga has a core rotation mechanism that continually rotates the pencil lead as you write. a spring-loaded clutch twists the lead incrementally
uni mechanical pencil kurutoga pipe slide model 0.5mm, black body (m54521p.24)
Kuru Toga Pencil - Tokyo Pen Shop
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Uni KURU TOGA Mechanical Pencil M5-452 0.5mm Lead Core Low Center Of Gravity Rotation lapicero School Supplies Japan Stationery - AliExpress
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Japan Uni Mechanical Pencil Kuru Toga Pipe Slide Model 0.5mm Lead Lead Rotating Technology Press Pen Lapiseiras Matite - AliExpress
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Self portrait of Uni Kurutoga Pipe Slide : r/mechanicalpencils
Japanese Uni Mechanical Pencil Kuru Toga 0.5MM Leads M5-452 Automatic Rotation Writing Constant Core School Stationery Supplies - AliExpress