Tokyo-based Wataru Architects has completed a major renovation of the Kitaoka Group Head Office Building in Mima City, Japan, featuring a spectacular 164-foot-long skylight that runs the entire length of the structure. The innovative design transforms the 40-year-old construction company headquarters into a light-filled workspace that connects employees with the surrounding natural landscape and local community.
The architectural renovation involved splitting the existing prefabricated steel structure into two narrow halves, creating a design that mirrors the valley formations along the nearby Yoshino River. At the center of this division, the architects introduced a dramatic atrium topped by the continuous skylight, which floods the interior spaces with natural daylight throughout the day.
"The project aims to redefine the values of working environments in Japan, starting from the local context," explained Wataru Sato, principal architect at Wataru Architects. "This integration embraces the surrounding natural landscape and fosters communication among employees, their families and the broader community." The central atrium serves as more than just an aesthetic feature, connecting the ground and first floors while enabling natural ventilation that improves what was previously described as a dark and disconnected layout.
The renovation prioritized environmental sustainability by retaining the majority of the original structure and finishes while maximizing natural lighting and airflow. "The existing building has been transformed by a luminous void that draws daylight and a breeze deep into the interior," Sato noted. "As the atrium spans the full depth of the building, airflow is evenly dispensed, delivering a gentle breeze to every corner." This natural ventilation system eliminates the need for daytime artificial lighting and significantly reduces air conditioning requirements depending on seasonal conditions.
The interior design features a minimalist approach that combines original tiling with plywood panels and neutral finishes, contrasted by red-painted structural beams and strategic placement of greenery throughout the space. The centerpiece is a 23-foot-tall Benjamin tree positioned at the heart of the floor plan, surrounded by various plants distributed across the interior spaces. "The palette embraces low-contrast tones, blending diverse textures and layered paint hues to create depth," Sato explained.
The ground floor has been designed as a public space where employees can work while remaining open to family members and community visitors, fostering a sense of connection beyond traditional office boundaries. The building's exterior has been updated with a 16-foot-long cantilevered canopy at the entrance, while the facade features new operable glass sashes that invite natural airflow into the building.
Surrounding the entrance, the landscape has been transformed into a community park featuring layered vegetation and what the architects describe as "an oversized 3D-printed vase." This outdoor space serves the local community and reinforces the building's role as more than just a workplace, but as a community gathering point that bridges the gap between private enterprise and public benefit.
The Kitaoka Group office headquarters renovation has been shortlisted in the small workplace project category of the Dezeen Awards 2025, competing alongside other innovative workplace designs including an experimental whisky lab by Barthélémy Grino and JSa's self-designed studio in a converted Mexican factory. The project represents a significant achievement in sustainable renovation practices and community-centered workplace design in contemporary Japanese architecture.
