In 1909, he became one of the founding members of the literary magazine, Subaru (The Pleiades), where he published his first collection of verses, Jashumon (Heretics), which took the poetic world by storm.

Through the use of its rich imagery and innovative structure, it (along with Yosano Akiko's Midaregami), is credited by critics with having set a new baseline for modern Japanese poetry.

Though the charges were later dropped, the experience was traumatic, as it was mentioned briefly in his first tanka anthology, Kiri no hana (Paulownia Blossoms, 1913), as having led to a religious influence in his outlook on life.

This became evident in his second anthology, Shinju Sho (Selection of Pearls, 1914), and his third, Hakkin no koma (Platinum Top, 1915), which include one-line poems in the form of Buddhist prayers.

He strove for what he called “oriental simplicity”, a concept which he borrowed from his understanding of Zen in Suibokushu (Collection of Ink drawings, 1923) and Suzume no tamago (Sparrow's Eggs, 1921).

In addition to his writings, he also edited the poetry magazine Chijo junrei (Earthly Pilgrimage), which enabled later authors, such as Hagiwara Sakutaro to get their start into the literary world.

The Nihon Densho Doyo Shusei [Collection of Traditional Japanese Nursery Rhymes], a six-volume publication edited by Kitahara, finally came out in 1976.

An annual festival[permanent dead link‍] celebrating the life and works of Kitahara is still held in his hometown of Yanagawa during the month of November.