Tombow Mono Zero Round Tip Retractable Eraser
Another tool that I can't live with is this ultra-slim retractable eraser. I particularly love it for tidying up illustrations or pencil guidelines. It is specially designed for precise erasing, it allows you to remove mistakes without damaging the rest of your work.
This design is long-lasting, and you can get refills for it (coming soon!) This is the finest eraser I have found with an ultra-fine 2.3mm round tip.