This article discusses the role of cats in the poetry of Hagiwara Sakutarō. It first touches on the fact that cats became a literary topic in Wagahai wa neko de aru by Natsume Sōseki, followed by an analysis of the second-most-famous cat in Japanese literature, appearing in two poetry collections of Hagiwara Sakutarō, Tsuki ni hoeru (Howling at the Moon, 1917) and Aoneko (The Blue Cat, 1923). I argue that Hagiwara uses cats to convey the emotions of a man affected by prostration and weakness, living alone in utter solitude. The cat symbolizes a world of illusion and suffering. Although it is not possible to closely define the meaning of Hagiwara’s “blue cat”, as this was a concept born within the passive ennui and the feeling of a man who is disillusioned and solitary.