明治32年（1899）、横浜市に生まれる。本名正雄。軒号百翠軒。横浜市不老町の生まれだが、少年時に日本郵船に奉職していた父の転勤に伴い、神戸に移住。兵庫県立一中に学び、園芸部に籍を置くが病気のため中退。花の道で身を立てることを決意し、神戸で真華池坊の生花と小原流の盛花瓶花を教授していた金子静風に入門。
進歩は著しく、金子静風の推挙によって二世光雲家元の直弟子となり、このとき同じく家元直門であった守下雨江を知り親交を結ぶ。大正11年、家元直門としての修業を終え、横浜市戸部町に移り、23歳にして小原流盛花瓶花の教授を始める。
翌12年3月、東京赤坂田町に転居するが、9月の関東大震災に遭遇、東京の状況を二世家元に報告のため汽車を乗り継いで下阪、護身のため家元から日本刀を譲り受け、佩刀（はいとう）して帰ったという逸話を持つ。大震災後、青山に移り社中「研美会」を創設、会長となる。また横浜にも横浜研美会を設立。花技のみならず日本画・洋画・陶芸・彫刻などいずれも余技の域を脱していた。園芸についても研究を積み、住居の東京市外玉川村（現・世田谷区用賀）に数百坪の花圃を持っていた。
大正12年、同志を集め、東京国風会設立懇請の連判状を作って家元の許可を願い出、翌13年に全国初の支部組織「東京国風会」を結成、弱冠25歳にして幹事長に就任し、関東における小原流の拠点を確立した。
昭和3年（1928）、研美会展を丸ビルの丸菱で開催。昭和4年5月、研美会に伍す大社中・一葉会の筆頭幹部である関光園と結婚し、小原流のみならず花道界の大きな話題となった。しかしその4か月後、妻・光園に後事を託し30歳の若さ夭折（ようせつ）でした。

Kudo Koshu was born in 1899 in Furo-cho, Yokohama as Kudo Masao. His flower name was Hyakusuiken. He moved to Kobe at a young age when his father was transferred by the shipping company, Nippon Yusen. Due to an illness, his horticulture studies at the Kobe Hyogo Prefectural Middle School were cut short. Determined to pursue a career in ikebana, he became a student of Kaneko Seifu who taught Shinka Ikenobo shoka style as well as the Ohara School moribana and heika styles in Kobe.
From the start, Koshu’s talent was obvious and he made rapid progress. Upon the recommendation of Kaneko Seifu, he became an apprentice to the Second Headmaster Koun. Morishita Uko was also studying under Koun at the time, and they became friends.
Koshu completed his studies under the Second Headmaster in 1922 and returned to Yokohama at age 23 where he began teaching moribana and heika in Tobe-cho.
In March 1923, Koshu moved to the Akasaka Tamachi district of Tokyo. In September, the Great Kanto Earthquake struck the capital. Koshu embarked on an arduous train journey to Osaka to inform Koun of the situation in Tokyo. He reportedly asked Koun for a Japanese sword to protect himself during his journey back to Tokyo. He returned to Aoyama where he founded and became Chairman of the Kenbikai group. He formed a Kenbikai group in Yokohama as well.
Kudo’s talents knew no bounds.In addition to being a masterful ikebana artist, Koshu excelled in Japanese painting, Western painting, pottery and sculpture. He also studied horticulture extensively; his home in Tokyo’s Soto Tamagawa-mura (currently Yoga in Setagaya Ward) had a garden that measured several hundred tsubo (one tsubo equals 0.30 square meters).
In 1923, Koshu gathered fellow Ohara School colleagues. They sent a sealed covenant to the Headmaster asking for permission to form Tokyo Kokufukai. The request was granted, and Japan’s first chapter organization was born in 1924. Koshu became the group’s first Secretary General at the young age of 25, and consolidated Ohara School’s base in the Kanto region.
In 1928 the Kenbikai Exhibition was staged at the Marubishi store in the Maru Building. The following year, Koshu married Seki Koen, the Managing Director of the Ichiyokai, a group of similar standing as Kenbikai; the marriage was much talked about within the Ohara School and the entire ikebana community. Tragically, Koshu passed away four months later at the young age of 30, leaving his wife Koen to carry on his legacy.
出典：花伝百選