The project redevelops a speculative office building in ICHIBANCHO, Tokyo, near HANZOMON Station. While conventional multi-tenant office buildings accommodate diverse companies, their architecture often conceals this diversity and contributes little to the surrounding streetscape. This design redefines the office building as a connector between people and the city through integrated bay windows and landscape. The façade consists of precast concrete panels with U-shaped cross-sections, using only four reusable formwork types. These panels extend into the interior as furniture-like bay windows that support diverse work styles while making workplace activities visible from the street. The dynamic façade expresses each tenant's identity and enlivens the streetscape. The landscape responds to ICHIBANCHO's sloping topography by creating outdoor spaces. A ground-floor café opens onto a semi-outdoor office approach, encouraging interaction among office workers, local residents, and visitors. The building also incorporates operable windows for natural ventilation, an air-based radiant air-conditioning system, floor-specific color schemes, and wayfinding that encourages stair use. Together, these strategies achieve a Building Energy Index (BEI) of 0.58, equivalent to ZEB Oriented performance, and earned WELL v2 WELL Core Platinum Precertification. The project demonstrates how a speculative office building can enhance occupant well-being, environmental performance, and urban life.