Sōma was born as Hoshi Ryō (星良), and was the samurai in the service of Sendai domain, and her mother was a scholar of Chinese classical literature.

She was given the pen name of Kokko by one of her teachers, with the cautionary note that for women authors, only a moderately shining light would be considered acceptable by society.

In 1898, she married Aizō Sōma, a follow Christian, and moved to what is now Azumino, Nagano, where her husband was combining social activism with sericulture.

The atelier grew to become a literary salon, whose members included Naoe Kinoshita, a socialist activist from Sōma's home town, Vasili Eroshenko, a blind Russian poet, as well as actress Sumako Matsui, painter Tsune Nakamura, poet and sculptor Kōtarō Takamura.

Bose was the mastermind behind a number of bomb plots against the Viceroy of India and attempts to organize an uprising against the British Raj.