A day for sharpen lead!

A mechanical pencil is pencil that looks like a pen, that uses a knock button (or twisting or shaking depending on the model) to push the lead forward. In Japan, they are called "sharp pen". The lead inside is called sharpen lead.

Today, and January 11th annually, is sharpen lead day シャー芯の日. The reason mechanical pencils are called sharp pens in Japan is because the lead was designed to always be sharp. In other words, you don't need a sharpener with one.

The reason January 11th is sharpen lead day is because a single pencil lead resembles the number 1, and the repeating ones evoke the image of multiple leads lined up. It’s a playful, visual connection that makes the date easy to remember. The anniversary was registered by Pentel, a leading manufacturer and contributor to the evolution of mechanical pencils.