Kukai is famous as there is proverbs such as "KOBO mo fude no ayamari"(Even Homer sometimes nods) and "KOBO fude o erabazu"(A bad workman blames his tools) as the expert of calligraphy.
It was an excellent calligrapher who was called "Sanpitsu"(Three brushes) with a coetaneous SAGATENNO emperor and TACHIBANANOHAYANARI.
The legend that he wrote five lines with five brushes in the mouth with right and left hands and feet at a time is handed down, too.
To decorate the gate of Kyoto, the emperor ordered him to write the character one day. However, one point of the character did not suffice when having hung a plaque.
Then, Kukai threw out the brush and wrote the point.
The proverb"KOBO mo fude no ayamari"(Kobodaishi also occasionally makes a mistake. Even Homer sometimes nods.) arose from this story.
He went to China as Japanese envoy to Tang Dynasty China, learnt how to make the brush, and took it home to Japan.
The calligraphy of in existence Kukai is specified for the national treasure.