Onigawara are "demon tiles" found most commonly on temple roofs, but also on some shrines and even private dwellings.
They are found at the end of roof ridges and were originally wooden boards used to protect the roof from the weather. Tile came to be used and were decorated with flowers and other designs.
From the kamakura period the demon design became popular and in some ways are analogous to gargoyles in the European tradition.
The first and second photos are from Temple 3 Konsenji. The third photo is from Aizen-in, the fourth from temple 5 Jizoji, and the last photo is from the main gate of Temple 8 Kumadaniji