He liberated Japanese free verse from the grip of traditional rules, and he is considered the "father of modern colloquial poetry in Japan".

His unique style of verse expressed his doubts about existence, and his fears, ennui, and anger through the use of dark images and unambiguous wording.

He also contributed verse to Maeda Yugure's Shiika ("Poetry") and Chijō Junrei ("Earth Pilgrimage"), another journal created by Hakushū.

In 1917, Hagiwara brought out his first free-verse collection, Tsuki ni Hoeru ("Howling at the Moon"), which had an introduction by Kitahara Hakushū.

The work met with much critical acclaim, especially for its bleak style, conveying an attitude of pessimism and despair based on modern Western psychological concept of existential angst influenced by the philosophy of Nietzsche.

There is a preface to Tsuki ni Hoeru ("Howling at the Moon") written by Hagiwara added in the New York Review Books' 2014 Cat Town (a collection of a number of his works).

His critical study Ren'ai meika shu ("A Collection of Best-Loved Love Poems", 1931), shows that he had a deep appreciation for classical Japanese poetry, and Kyōshu no shijin Yosa Buson ("Yosa Buson—Poet of Nostalgia", 1936) reveals his respect for the haiku poet Buson, who advocated a return to the 17th century rules of Bashō.

[4] Ineko deserted her family for a younger man in June 1929 and ran off to Hokkaidō and Sakutarō formally divorced her in October.