In traditional Japanese Tebori tattooing, kaeshibari is the practice of flipping tattoo needles to use the ink on the other side.
To tattoo details, some tattooists use a separate tool consisting of only 3 needles. But the professional Japanese Tebori tattooists can tattoo whatever they want using only one set of needles for outlining. They don't have to use other tattooing tools. They can tattoo any thin or thick lines, small circles and so on. The professional tattooists tattoo the designs on the skin smoothly, from up to down, down to up, right to left, left to right. When more ink is needed after tattooing from left to right, for example, one does kaeshibari, flipping the needles. Kaeshibari is one of many professional techniques, which is flipping the other side of the needles and tattooing by using the rest of the ink on the other side.