As you maybe already know, the Japanese people worship a weird mixture of shamanistic Shinto as well as Buddhist gods. Along with the dozens of gods with large names and long titles usually ending in -kami (神) or -mikoto（尊） (like Amaterasu Omikami or Tsukiyomi-no-Mikoto), there are myriads lesser spirits.
Japan has a lot of water. Japan has a lot of mountains. Japan also has a lot of deities. This abundance means that while spending time on the mountains it is highly possible to come across stone plaques or even stone statues commemorating larger or lesser spirits or dignified humans. Below you can see a statue of Daikokuten (大黒天), ‘the god of the big black’, namely of wealth, famous for his large belly and his hammer. This statue, together with another 6 of them (I think) , representing the 7 gods of fortune (七福神) was located next to lake Hokuryu (北竜湖) at Nozawa-Onsen, Nagano.
Sometimes, instead of gods, a statue of a local spirit is placed next to large bodies of water, lakes or ponds. This statue of a fair lady was noted in the map of Hacho pond (八丁池) on Mt. Amagi, Izu, as Suijin-san (水神さん) or Mrs Water spirit. Usually, Suijin is the manifestation of the benevolent divinity of water in Shinto practice. Stone markers or sculptures related to the water god can be found at random locations in the countryside, from canals and mountain springs to wells or inside sewages.
If you ever visited a Japanese shrine, you probably noticed a slender dragon greeting you at the entrance gate, guiding you through the purification ritual. Well, Ryujin (竜神), the dragon god, is often associated with water and you might find him also in the wild, close to waterfalls. If you pay attention, you will notice that the character for dragon 竜 is really similar to the character for waterfall 滝, it is basically a dragon with the water radical on the right. Above you can see a small dragon statue located next to a waterfall on the path to Mt. Oyama in Kanagawa.
A couple of times, if the waterfall is especially important, apart from a statue, a small shrine or even a torii gate might be erected next to it. A lot of times, the shrine is decorated with paper origami talismans, shaped like a thunder, called shide (紙垂). You can see that this waterfall close to lake Soji, on the foot of Mt. Fuji in Yamanashi has both as small shrine with a torii and a small suijin statue.
Apart from water, mountains are also abundant in Japan and so are the mountain gods or Yama no kami (山の神). Their statues promise safety and godspeed to hikers. Conversely, passerby’s throw coins to and around the statue of the mountain god as gratitude for their protection. If you are especially grateful -or scared- you can leave food or sake at the foot of the statue, or even build a small tower of stones. Moreover, the mountain spirits can be of Buddhist origin, like the one on the left, or of Shinto origin like the one of the right. Both statues are from location on the Tanzawa mountain range in Kanagawa, the first at the top of Mt. Tanzawa and the second on the way to the top of Mt. Oyama.
Other times, you might find something tinier and cuter than an old stone statue. Like that one time that on the way to Koburi pass, I found two small tanuki figures carefully placed on the remainders of a tree bark. Tanukis are considered friendly and are often placed at shop entrances to welcome customers. However, I’ve never seen one randomly on a mountain before. Unfortunately, all the consequent times that I visited that path, the tanuki figures were never there.
The most common type of statue is arguably the jizo (地蔵). This variety is easily recognizable because they are usually dressed up with red caps and aprons. They can be ancestor spirits or general guardian spirits and are usually there to protect a road or a mountain path. In the later case, they are called Dōsojin (道祖神), whereas as protectors of unborn children they are called Mizuko kuyō (水子供養). The red clothes are usually an offering from distressed or bereaving parents. Although of uncertain Buddhist origin, the jizo have been incorporated in Japanese reverence in the past centuries. This remarkably long row of jizo is guarding a volcanic crater with the ominous name Kanmangafuchi Abyss in Nikko, Tochigi.
Sometimes, in order to thank the jizo for their protection, one can put various offerings in front of them, most commonly sake. On my way down from Mt. Kobotoke Shiroyama, I saw well dressed jizo, one with glasses, in front of whom were a cup of sake, tangerines and 5 yen coins. One, maybe in relation to protection on a child, had a kokeshi doll and a child’s handkerchief at its feet.
Last is the magnificent and so popular that has its own emoji, the Tengu 👺. You can recognize a Tengu (天狗) or Heavenly dog, from its large nose and sometimes red face. In contrast to their name, the Tengu have bird-like traits such as beaks and wings, while maintaining a human torso. Even though tengu belong to the Yokai class of demons, they are sometimes worshipped as gods. Mt. Takao is especially famous as a place of worship for Tengu, having two large statues of a great red tengu and a lesser green tengu at the entrance of temple on the top. Interestingly, if you try to venture a little further from Takao, to Mt. Shiroyama (城山 or caste mountain), you will come across an 1m tall wooden, angry-looking tengu jizo.
This impromptu list of stone statues and other spirits is only the tip of the iceberg, in the vast sea of Japanese folklore and tradition. Did I miss your favorite guardian spirit? Tell me more in the comments. Oh, and if you come across a spirit statue in the forest, consider leaving a coin or some candy as a backup safety measure.