kaisho

(JP: 楷書; PR: "kai-shoh")
The most recent of the Chinese styles of writing kanji. Kaisho, or "regular script," evolved from its predecessors around 450 CE.

Many calligraphers regard the forms of kaisho that were developed during the Tang dynasty as the archetype of this style and (possibly) the most perfect of all the styles of calligraphy. As a consequence, such forms have almost always been the ones that students of calligraphy have begun by learning. The ubiquity of this style is why it is referred to as "regular" or "standard" in English.