Kunrei-shiki romanization is the system for romanizing Japanese characters officially promoted by the Japanese government and taught in schools. It's intended to maintain consistency with the way kana are written without being a literal representation of the way the syllables actually sound (e.g., "sa", "si" and "sya" instead of "sa", "shi" and "sha".) For this reason, many English speakers find that it looks strange and prefer to use Hepburn romanization, which is also used in the spelling of tags throughout Danbooru.
