- He is considered as the most influential father figure of modern Japanese poetry.
- His original aspirations was to become a musician; after failing Japanese-language courses in Tokyo, Hagiwara primarily lived on his father's financial resources while taking guitar and mandolin classes. He later founded a mandolin orchestra in his hometown, Maebashi. His lifestyle was criticised by his childhood acquiantaces, and many of his early poems included harsh remarks about these criticisms.
- His poems are infused with a musical qualities; this stemmed from his early exposure to music and literary arts: he played the harmonica and other instruments at the age of eight, and was writing waka by the age of fifteen.
- His father's occupation as a doctor influenced Hagiwara's fascination with disease. One such example can be found in his poem, "The World of Bacteria".
- His literary career began in 1913, after publishing five verses in Zamboa, a prestigious Tokyo magazine edited by Kitahara Hakushuu
- While he was most productive and inspired in the years 1913-15, it coincided with a period of self-diagnosed "nervous system disease". This "disease" caused him great pain and produced nightmarish visions and hallucinations.
- Hagiwara Sakutarou, Muroo Saisei , and Yamamura Bochou established the "Merman Poetry Group", dedicated to studying music, poetry, and religion. Their literary magazine, published in 1915, was titled "Tabletop Fountain".
- Muroo and Hagiwara further co-founded the literary magazine, "Sentiment", centred on the new style of modern Japanese poetry in which Hagiwara was developing.
- "Howling at the Moon" is considered the first successful book in colloquial free verse; he established a new style of poetry that incorporated free verse, colloquial language, and onomatopoeia. It is preluded by an introduction by Kitahara.
- He, along with Miyoshi Tatsuji , founded a critical journal, "Poetry and Poetic Theory" in 1928.
- His poems are often dark, containing elements of morbid fantasy, fin-de-siècle decadence, and juxtapositions of everyday things and natural processes. His poems often strayed away from their topical subject matter, instead alluding to indeterminate symbolism.
- One of his original poetic device is the repitition of the infinitive form of a verb; this is exhibited in poems such as "Bamboo".
- His influence was prevalent amongst contemporaries; Miyoshi's poem, "Hagiwara Sakutaro Sensei" expresses his debt to Hagiwara; other authors who were inspired by his works include Ito Sei and Nishiwaki Junzaburoo
- He died at age 56 due to pneumonia.