At the age of one in 1868, her father left the family as an espionage agent, serving the Aizu clan against the revolutionists during the Boshin War, and the next year, he was relocated to Tonami (present-day Mutsu) with his feudal lord.

Her stepfather died in 1883, and in 1885 her natural father Matsukawa Katsujirō restored Kashi to his family register in Tokyo where he lived.

Kashi met Iwamoto Yoshiharu when he lectured at her school, and in 1886 he published two of her articles in his magazine[6] Jogaku zasshi; a travelogue 旧き都のつと (The Product of the Old City) in the 23rd issue,[7] and in the 37th In Memoriam—Condolence Poem (木村鐙子を弔ふ英詩), a mourning poetry written in English dedicated to Yoshiharu's friend the late principal Kimura Tōko of Meiji Girls' School.

Yoshiharu was the editor in chief at Jogaku zasshi since 1886, as the co-founder and his friend Kondō Kumazō had died that year.

There are over 50 literature she published on Jogaku zasshi with the most popular translation of Little Lord Fauntleroy written by an American novelist Frances Hodgson Burnett.

[note 3] Starting in 1894 when she was 30, she edited those columns for women and children in a journal The Japan Evangelist and posted some 70 essays introducing Japanese books, annual events and customs in English.

A fire broke out at Meiji Girls' School in February 1896, and five days after that, Wakamatsu Shizuko died due to heart attack.