 In 1870, Shimooka Renjō invited Yokoyama to join him in photographing Mount Nikkō-Shirane.The resulting photographs, under both their names, were subsequently presented to the Tokugawa clan.Yokoyama opened an art school in 1873 whose students included such painters as Kamei Shiichi, Kamei Takejiro and Yamada Nariaki, and such photographers as Azusawa Ryōichi, Kikuchi Shingaku, Nakajima Matsuchi, and Suzuki Shin'ichi.