A sleeve-type pen case that can store one writing instrument at a time. Its simple design, without flaps or zippers, allows for smooth insertion and removal of writing instruments while protecting them. The outer material is smooth leather with a beautiful, moderately firm texture, and the lining is made of soft microfiber. The leather is from Monfrini Perami, a long-established tannery in Milan, Italy, and is characterized by its beautiful and vibrant colors.