top of page






To capture and enhance the potential of a place.

To build a rich relationship between the outside and the inside.

A simple form that will not fade over time.

A generous and tolerant place to live.

We are an architectural design office based in Tokyo and Wakayama, aiming to create such architecture.


2024.4 明星大学建築学部建築学科 非常勤講師に着任します。設計製図課題を担当します

2024.4 中央大学理工学部都市環境学科 兼任講師に着任します。空間設計実習を担当します

2024.3.15 「デザイナーズFILE 2024」がカラーズより出版されました。3作品が掲載されています

2024.2.7-2.11 渋谷区北谷公園にて「Park(ing)Day、まちをかえる」展が開催されます。会場構成/什器デザインを担当しています

2023.12 「パブリックスペース活用事典」が学芸出版社より出版されました。メルボルンについて2ページを執筆しています



2021 東京都内某認可保育所 整備運営事業者公募 最優秀案選定 (YTTと協働)

2021 Park(ing)Day Japanとしての活動:2021年度グッドデザイン賞

2020 丹波山村新庁舎建設計画プロポーザル:次々点 建築ジャーナル2020年10月号 掲載 (YTTと協働)

2012 Vertical Cities Asia2012 国際デザインコンペ 佳作 (葛西慎平、高橋宇宙と協働)

2013 「人があつまる大井町駅前中央通りアイデアコンペ」ファイナリスト


2022 白花亭*:日本建築学会作品選集2021-2022 掲載

2020 白花亭*:archdaily掲載年間トップ100 選定

2019-2020 白花亭*:architecturephoto , dezeen, archello, designboom, ELLE DECOR ITALIA, その他メディア多数掲載

2019 白花亭*、ハートハウス成城 はあと保育園成城*:雑誌KJ 2019.10掲載

2019 グループホーム楽し愛*:2019年度岡山市景観まちづくり賞

2018 垂水市新市庁舎設計プロポーザル*:ファイナリスト 

2015 三保松原ビジターセンター設計プロポーザル*:最優秀案

2013 美波町医療保健センター設計プロポーザル*:ファイナリスト


2021 Selected as the best proposal for a licensed nursing school project in Tokyo (work with YTT)

2021 Activities as Park(ing)Day Japan: Good Design Award 2021

2020 Proposal for the construction of a new government building in Tabayama Village: selected as the third best proposal (work with YTT).

2013 Vertical Cities Asia2012 International Design Competition, Honorable Mention (in collaboration with Shimpei Kasai and Cosmo Takahashi)

2011 Finalist, "Idea Competition for Oimachi Station Central Avenue, a place where people gather"


2022 White Flower Arbor*: Published in the Architectural Institute of Japan, Selected Works, 2021-2022

2020 White Flower Arbor *: archdaily publication, selected as one of the top 100 of the year

2019-2020 White Flower Arbor *: published in architecturephoto , dezeen, archello, designboom, ELLE DECOR ITALIA, and many other media

2019 White Flower Arbor *, Heart House Seijo and Heart Nursery School Seijo*: published in magazine KJ 2019.10

2019 Group Home Tanoshiai*: 2019 Okayama City Landscape Town Development Award

2018 Tarumi City New City Hall Design Proposal*: Finalist 

2015 Miho Matsubara Visitor Center Design Proposal*: Best Proposal

2013 Minami Town Medical and Health Center Design Proposal*: Finalist

*Works for which I was in charge during my tenure at APL Design Workshop


2024- 中央大学理工学部都市環境学科 兼任講師 (空間設計実習を担当)

2024- 明星大学建築学部建築学科 非常勤講師 (設計製図を担当)

2021 鳥取WEDOエリアマネジメント ゲストレクチャー

2020- ソトノバ・スタジオ|Park(ing)Dayクラス プロデューサー

2017 日本建築学会特別企画 パラレル・セッションズ2017 参加

2024- Part-time Lecturer at Chuo University, Japan

2024- Part-time Lecturer at Meisei University, Japan

2021 Tottori WEDO Area Management Guest Lecture

2020- Sotonoba Studio|Park(ing) Day Class Producer

2017 Participated in Parallel Sessions 2017, a special project of the Architectural Institute of Japan





1987 和歌山県和歌山市生まれ

2006 智辯学園和歌山高校卒業

2010 東京大学 工学部建築学科卒業

2010-11 リスボン工科大学建築学部|ポルトガル 留学(AUSMIP)

2013 東京大学大学院 新領域創成科学研究科 社会文化環境学修了

2013-2019 株式会社アプルデザインワークショップ(大野秀敏氏に師事)

2021- icai architects 開設

2024- 中央大学 兼任講師

2024- 明星大学 非常勤講師

icai architects 代表 一般社団法人ソトノバ




Yohei Ikai

1987 Born in Wakayama City, Wakayama Prefecture

2006 Graduated from Chiben Gakuen Wakayama High School

2010 Graduated from University of Tokyo, Faculty of Engineering, Department of Architecture

2010-11 Studied abroad at the Faculty of Architecture, Technical University of Lisbon, Portugal (AUSMIP)

2013 Completed Graduate School of Frontier Sciences, The University of Tokyo

2013-2019 APL Design Workshop, Inc. (Looking up to Prof. Hidetoshi Ohno)

2021- Established icai architects

2024- Chuo University Part-time Lecturer

2024- Meisei University Part-time Lecturer

Representative of icai architects, Partner of Sotonoba

*First-class architect, managing architect, member of architects' liability compensation system

Member of the Tokyo Society of Architects and Building Engineers, Tokyo Society of Interior Planners, and the Architectural Institute of Japan.


icai architectsは東京と和歌山を拠点に、建築/都市/インテリアにまつわるものやことをデザインする一級建築士事務所です。


icai architects | icai一級建築士事務所

所在地:東京都文京区白山5-1-15 2階TOKYOKENCHIKUPLUS内

    東京都中野区 / 和歌山県和歌山市

登録番号:一級 東京都知事登録 第64258号









icai architects is a first-class architect office based in Tokyo and Wakayama, designing things related to architecture, urbanism, and interior design. We are available for consultation from all over the world, so please feel free to contact us.

icai architects

Location: Nakano-ku, Tokyo / Wakayama-shi, Wakayama

*Please inquire for location details.

Registration No.: First class, Tokyo Governor Registration No. 64258

Opening date: March 2021

Business Activities:

Design, construction supervision, research, planning, consulting, book editing and publishing, etc. of

-Architecture (new construction/renovation and expansion of existing buildings, etc.)

-Landscape design

-Interior design


-Urban and regional scale planning




















1. Initial meeting

2. Initial presentation: ~1 month

 Based on your request, after site survey and regulation check, we will propose a design, and you can decide whether you would like to entrust us with your project.

3. Signing of design and supervision contract

4. Basic design: 2 to 3 months

 While making various adjustments, we determine the basic shape of the building.

5. Detail design: 2 to 3 months

 We carry out detailed design and prepare drawings necessary for construction estimates.

For both basic and detail design, we regularly hold client meetings with models and 3D models.

6. Construction cost estimation and adjustment: 1-2 months

 We request contractors for construction cost estimates. After assessing the estimates and adjusting for reductions, a contractor is selected.

7. Confirmation application: 1-2 months

 We complete various legal procedures and prepare for the construction.

8. Construction supervision

 We visit the site about once a week to confirm that the construction is being carried out according to the drawings in cooperation with the builder. Client meetings are held on a regular basis.

9. Handover upon completion of construction

 After statutory, designers, and client inspections, the architecture is handed over to the client.

*Design construction period depends on the type of project, so please contact us for details.



The standard design and supervision fee is approximately 5-15% of the estimated construction cost (interior design will be discussed separately). The fee is based on the standard for professional fees set by the Ministry of Land, Infrastructure, Transport and Tourism, but it depends on the type, scale, and circumstances of the project, so please contact us for details.



Please feel free to contact us using the contact form below or at

下記コンタクトフォーム、もしくは までお気軽にどうぞ。



bottom of page