This project is a landscape design to restore the garden of the Tojo Residence which was designated as one of the national places of scenic beauty. At the beginning of the project, the restoration of the garden was planned based on the historical literature and a large number of photographs taken by Akitake Tokugawa, the last man who would be the Shogun, who created this place as his retirement residence. However there was no drawing plan of the garden, it was unsure where the photographs were taken, and it was difficult to obtain the same materials as when the garden was created. Therefore we aimed to find out the essential value of the garden and restore it, rather than reproducing the garden shown in the old photographs. Even before the project started, the two researchers; Mr. Yoichi Saito, the Honorary Director of the Tojo Museum of History, and Mr. Eijiro Fujii, the Professor Emeritus of Chiba University had researched the garden and advocated the solution to restore the essential value of the garden. So based on their research, we proposed a method to restore the garden from the viewpoint of a landscape architect, and had multiple discussions with the two researchers as "a joint researcher." After deep consideration and verification, we created the construction documents to realize the restoration and conducted the construction administration at the site. Regarding the "joint research," although the official content of the project was not "joint research," we think it is the key feature of the project since the client evaluated that our role for the project was a joint researcher who fed back our knowledge, technology and thought from the viewpoint of a landscape architect to the restoration of the garden. As for the construction administration, we believed that it is important to keep considering the detail of the restoration design even while the site is changing due to the basic construction work such as cutting down unnecessary trees, transplanting, and land forming, so we proposed its importance to the client and we were entrusted to do the construction administration. In addition, to transplant the trees, a long time was required for the trees to root, so we proposed to the client that the construction work should be carried out over two years and made better restoration work.