In 1912, Kitahara was arrested for adultery and jailed for two weeks. 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).