This is the open mouth Deva known as Agyo in the Nio-mon.
Kotoku-in is a Jodo temple in Kamakura, founded in 1243. The original temple complex was destroyed by several storms, leaving its giant Daibutsu exposed. The Buddha statue has become one of the most popular tourist attractions in the Kanto area, and symbol of Kamakura. The great Buddha of Todai-ji in Nara was the original inspiration for the statue--it had been seen by Yoritomo and his wife Hojo Masako.
Kotoku-in. Kamakura, Kanagawa.