Sashiko needles are extra hard and sharp. They come in several different lengths for various types of sashiko stitching. The longest needles may take some getting used to, but they are practical for long straight stitches because it's faster when you can load extra many running stitches onto the needle before pulling the thread through. Sashiko stitching can also be curved and have many different patterns, in which case shorter needles are advisable.
You use a special thimble, which you can purchase from the brand Olympus in leather here, or in metal from Upcycle Stitches here.
These needles are from Upcycle Stitches, a Japanese, family-owned business. They are slightly thinner than the needles from Olympus. I recommend not using these for the very thickest jeans, but they are very good for slightly thinner fabrics, because they are even sharper and glide more easily through textiles as they are a bit thinner than those from Olympus. All three needles are the same length. They measure 53 mm.
The needle has a relatively large eye to accommodate sashiko thread, which is quite thick.