Koichi Sakao's artistic practice spans numerous long-term projects that explore the relationship between memory, place, and daily life. Among these, the Midori no Heya (Green Room) Project creates contemplative spaces where nature and interior environments merge. These installations invite viewers to pause and reflect, using greenery and light to transform ordinary rooms into meditative sanctuaries. The project exemplifies Sakao's belief that art can emerge from the spaces we inhabit daily, encouraging a deeper awareness of our surroundings and the quiet beauty that often goes unnoticed in modern life.

The Town Memory Project (Machi no Kioku PROJECT) documents the evolving landscapes of urban environments through meticulous artistic observation. Sakao works to capture the layers of history embedded in streets, buildings, and neighborhoods that face change or disappearance. By recording these transient urban scenes, he preserves fragments of collective memory that might otherwise be lost to redevelopment. This ongoing series reflects a deep commitment to honoring the stories held within physical spaces, inviting audiences to consider what is gained and what is lost as cities transform over time.

Niigata Water Memory Project traces the profound connection between water and community identity in the Niigata region. Through this work, Sakao explores how rivers, seas, and rainfall shape not only the physical landscape but also the cultural and emotional lives of those who live alongside them. The project incorporates elements of drawing, installation, and community engagement to create a multifaceted portrait of water's role in daily existence. It stands as a testament to the artist's interest in elemental forces and their power to bind people to place across generations.

The Ootanokakera project represents a sustained engagement with fragments and wholeness. The title itself suggests large pieces or shards, and the work investigates how broken elements can carry meaning and beauty. Through this lens, Sakao examines what remains after things fall apart and how those remnants can be reassembled into new forms of understanding. The project resonates with themes of reconstruction and resilience, inviting viewers to find value in incompleteness and to consider the stories that even the smallest fragments can tell about larger wholes.

Sakao's Ginza Frottage Plan extends his interest in surface, texture, and urban memory through the technique of frottage. By rubbing surfaces in the Ginza district, he captures the tactile imprint of one of Tokyo's most iconic neighborhoods. This method reveals hidden patterns and histories embedded in walls, pavements, and architectural details that might otherwise go unnoticed. The project transforms the act of walking through the city into an artistic practice, producing works that serve as physical records of urban life and the accumulated marks of time on the built environment.