After Todoroki Valley, I continued walking south until I reached the Tama River (多摩川). It is the same river that passes through Okutama and Ome. I then followed it until Tamagawadai Park, famous for its hydrangea (which bloom in early summer).
Lake Tama is an artificial lake in Higashiyamato City, in western Tokyo, right at the border with Saitama Prefecture. It was formed by damming up a river running through the Sayama valley, a project started in 1916 and completed in 1927. The lake now serves as a water reservoir for the residents of Tokyo.
The lake is surrounded by parks and forests and there is a popular cycling course extending from Nishitokyo City to Lake Tama. North of the lake towards Lake Sayama lies the Seibu Dome, home of the Saitama Seibu Lions baseball team. Also worthy of a visit are the buddhist Yamaguchi Kannon Konjoin (山口観音 金乗院) and Sayama Fudoson (狭山不動尊) temples.
The Otama Trail is in Okutama City, in Nishitama District, the westernmost area of Tokyo. It is a gentle path that follows the Tama River from Kori to Okutama through well-built trails, mountain roads and suspension bridges. I followed it for a short section, from Hatonosu to Shiromaru Dam. Autumn colors were not fully there yet but the sights were still great.