Katyayana also known as Mahakatyayana, Mahakaccana [Mahaakaccaana] and, in Japanese, as Kasennen, is one of the "Ten Disciples of the Buddha". (1) Mahakashyapa, 2) Ananda, 3) Shariputra, 4) Subhuti, 5) Purna, 6) Mahamaudgalyayana, 7) Katyayana, 8) Aniruddha, 9) Upali and 10) Rahula. He was foremost in explaining Dhamma. He was born in a brahmin family at Ujjayini [Ujjain] and received a classical Brahminical education studying the Vedas. Katyayana studied assiduously under Asita on Mount Vindhya, who had predicted that Prince Siddhattha would become either a cakravartin [a great wordly ruler] or a Buddha. With a group of seven friends he invited the Buddha to visit, and gained enlightenment (bodhi) while listening to him preach. He was ordained, and made numerous converts in the state of Avanti. Tradition attributes the authorship of the Nettipakarana, a work of grammar, and the Petakopadesa, a treatise on exegetical methodology, to Katyayana although these were most probably composed by a school descended from him.
He was a vegetarian and once contracted smallpox and was told by his doctor that he should consume goat's meat and goat's blood and that he should apply them to his skin. But the former answered that he would die rather than transgress the precepts. He did not eat the meat and so passed beyond suffering.