Izumi Kasagi (笠木泉) | Kishida Prize-Winning Playwright Guide

Introduction

Izumi Kasagi (笠木泉) is a Japanese playwright, director, and actor who leads the theater unit Sunūnū (スヌーヌー). She won the 69th Kishida Kunio Drama Award in 2025 for Umi made 100-nen (海まで100年, rendered here as 100 Years to the Sea), sharing the prize with Kei Ando (安藤奎), who won for Arukanakutemo Bō ni Ataru (歩かなくても棒に当たる).

Early Life and Career

Kasagi was born on January 4, 1976, in Fukushima Prefecture and graduated from Japan Women's University. While a university student, she began appearing in productions by Yuenchi Saisei Jigyodan (遊園地再生事業団), the company of the playwright and director Akio Miyazawa (宮沢章夫). She has since worked widely as an actor in theater, film, television, and animation voice work.

Her writing career developed alongside her acting. Her script Ie no Kagi (家の鍵) was shortlisted for the 6th Sendai Short Play Award. Sunūnū's first production, Dōdō (ドードー), staged in 2018, was a solo piece with a dancer. According to a review on artscape, the unit's name means "swallow" in Arabic.

Sunūnū's second work, Moscow no Umi (モスクワの海), was planned for December 2020, postponed because of the COVID-19 pandemic, and staged in December 2021. It was shortlisted for the 66th Kishida Prize. The review describes a 90-year-old woman who falls in the garden of her small, old house in a town across the river from Tokyo, the passerby who helps her, and a son who had long been a recluse and whom only his mother can see.

The Kishida Prize-Winning Work

Umi made 100-nen premiered from December 12 to 15, 2024, at Zou-no-Hana Terrace (象の鼻テラス). It was submitted to the prize as a performance script (上演台本), and it was Kasagi's second time on the Kishida shortlist.

We could not confirm a detailed synopsis of the play from a source we were able to read, so we do not offer one here.

Major Works

Dōdō (ドードー, 2018) - Sunūnū's first production.
Moscow no Umi (モスクワの海, 2021) - Shortlisted for the 66th Kishida Prize.
Umi made 100-nen (海まで100年, 2024) - Winner of the 69th Kishida Prize.
Hateshinai Heya (果てしない部屋, 2026) - A new script directed by Kae Inaba (稲葉賀恵) at the Kanagawa Prefectural Youth Center in February 2026.

Hakusuisha, the prize's organizer, also lists Nagai Jikan no Hajimari (長い時間のはじまり) among her main works.

How to Experience Her Work

Other companies have begun to stage the winning play. The Kyoto student company Gekidan Keppeki (劇団ケッペキ) performed Umi made 100-nen at THEATRE E9 KYOTO in April 2026. We could not confirm a published English translation of her plays.

To explore other Japanese plays, visit our script library.