Ioana Chinan and Kenji Hasegawa 長谷川兼司 are the founders of StudioOna & Hasegawa, a design–build practice based in the Berkeley, California. Their collaboration bridges design and craft, joining architectural vision with the precision and integrity of hands-on craftsmanship.
Ioana Chinan, founder and principal designer, brings over 15 years of experience in residential architecture and interior design across the U.S. and Europe. She holds a Ph.D. and a Master of Science in Architecture from the University of California, Berkeley, where she also taught architectural design and theory. Her research and teaching continue to shape a thoughtful, context-driven approach to design, one that values environment, material, and lived experience as much as form.
Before establishing StudioOna & Hasegawa, Ioana worked on a wide range of projects, from large-scale urban developments in Romania to custom home remodels throughout Florida and California. Her experience spans housing, hospitality, public interest design, and emergency shelter prototypes developed in response to natural disasters. At StudioOna & Hasegawa, she leads the design and permitting process, guiding residential projects through planning, zoning, and building approvals across multiple Bay Area municipalities. Her role bridges creative vision with technical execution, ensuring each project moves seamlessly from concept to construction.
Kenji Hasegawa, founder and principal builder, was born in Takasago, near Kobe, Japan, a place shaped by water, mountains, and the traditions of handcraft. As a boy, he built small wooden boats and watched them drift toward distant horizons, imagining the world beyond. That same curiosity and respect for making have guided his path ever since. Rooted in the spirit of Japanese craftsmanship, his work embraces the quiet beauty of natural materials and the mark of the hand.
For over a decade, Kenji was associated with Japonesque, a San Francisco gallery devoted to traditional and contemporary Japanese art and design. During that time, he created one-of-a-kind handcrafted pieces that merged Japanese traditions with the sensibility of California living.
As a California licensed general contractor [Lic #819759], Kenji Hasegawa leads the construction management arm of StudioOna&Hasegawa. His responsibilities include construction supervision, subcontractor coordination and management, material procurement oversight, and quality control across all projects. Kenji upholds the highest standards of workmanship, ensuring that every built detail reflects precision, integrity, and care.
An expert in carpentry, wood furniture, metal work, and welding, Kenji brings hands-on craftsmanship to each phase of construction. Guided by the wabi-sabi philosophy, he approaches every project with restraint, humility, and respect for natural materials. His work values simplicity, imperfection, and authenticity, qualities that bring balance and quiet beauty to both structure and space.
Through his object design practice, Kenji continues to create custom furniture and artwork, each piece crafted by hand and infused with the same attention to detail that defines his construction and artistic work. See some of the many objects he created and design under OBJECTS section from our site menu.
Together, Ioana and Kenji form a partnership grounded in shared values: professional integrity, craftsmanship, honesty, and a commitment to excellence. Their collaboration brings together two complementary perspectives: the architectural discipline of design and the lived wisdom of building. Each project becomes a conversation between drawing and making, concept and craft, resulting in spaces that are clear, balanced, and deeply human.
VALUES
Professional Integrity
We act with transparency and accountability at every stage. Our clients trust that our decisions reflect their goals and the enduring quality of the work.
We act with transparency and accountability at every stage. Our clients trust that our decisions reflect their goals and the enduring quality of the work.
Craftsmanship
We value precision and the art of making. Each drawing, connection, and finish reflects our commitment to excellence and respect for materials.
We value precision and the art of making. Each drawing, connection, and finish reflects our commitment to excellence and respect for materials.
Honesty in Design and Construction
We believe that beauty comes from truth in materials, in methods, and in communication. We advocate for clear intentions, honest budgets, and well built work.
We believe that beauty comes from truth in materials, in methods, and in communication. We advocate for clear intentions, honest budgets, and well built work.
Commitment to Excellence
Excellent work is thoughtful, durable, and responsive. Each project is a collaborative effort toward a lasting contribution, one that stands the test of time in both function and spirit.
Excellent work is thoughtful, durable, and responsive. Each project is a collaborative effort toward a lasting contribution, one that stands the test of time in both function and spirit.
We design with honesty, build with integrity and craft with purpose
CLIENT REVIEWS
Sharon W.
When you are spending thousands of dollars on house renovation projects, you want to get it right. So, my husband and I decided to hire a designer to help us pick the best materials for our projects. Ioana from StudioOna&Hasegawa was fully invested in our projects from the beginning. She was professional, knowledgeable and personable. We replaced our deck, our living room furniture and all the floors in our house. Ioana listened to our wishes and offered suggestions. She was patient and kind. She went to stores and showrooms with us to help choose our oak floors. She also went to the furniture store to choose our new family room furniture. She sent us a sketch of a design layout for our new deck with pictures of the many ways we could decorate the space. We used those ideas for décor and lighting. Ioana helped us make our home more comfortable and inviting. We are enjoying the re-designed spaces with family and friends. She exceeded our expectations, and we highly recommend her.
Jennifer D.
Ioana is an absolute joy to work with. She’s an extraordinarily knowledgable and gifted designer. Her intelligence and creative prowess made the process of designing our basement renovation a total dream. We trusted her insight and guidance, as she holds herself to an incredibly high standard. We feel so lucky to have found her and would work with her again in a heartbeat!
Martina F.
Working with StudioOna&Hasegawa on our window replacement and exterior upgrade was a pleasure. They brought a strong sense of design and building performance, helping us reimagine the façade for better curb appeal and improved energy efficiency. Their guidance through the permitting process was seamless—they coordinated with the city and handled all technical documentation with precision. Their responsiveness and ability to clarify complex decisions stood out, from selecting high-performance windows to addressing waterproofing and long-term durability. The result is a home that looks and performs better, fully up to today’s energy standards. We’re grateful for their thoughtful, expert coordination and highly recommend StudioOna&Hasegawa for anyone seeking a team that combines design vision with practical know-how