[The torii (鳥居)] does not demarcate something external into which I can simply tap. To function properly, the mysterious power beyond the torii must be in an internal relation with the person passing through it. If your mind is befuddled and clouded, if your heart is defiled and disingenuous, passage through the gateway will only return you to that. A symbol sacred to Shinto is the mirror. In fact, in many shrines, large and small, major and minor, the altar contains nothing other than a mirror. Along with the sword and comma-shaped jewel [magatama], the mirror is part of the official regalia of the emperor as chief priest of the tradition. A mirror's capacity to reflect depends on its cleanliness. Hence Shinto sites usually have a water trough for purification near the entrance. As people enter the heart of the shrine, they are expected to wash their hands and mouth, cleansing themselves of any pollution from physical or verbal misdeeds. Washing away dirt from the journey, they are ready to be a home in the kami-filled, tama-empowered shrine. Their hearts and minds are pure. Even the torii along the path on Mount Fuji serves a similar function. The torii reminds pilgrims to cleanse their inner self in preparation for approaching the peak.SOURCE: Shinto: The Way Home, by Thomas P. Kasulis (U. Hawai‘i Press, 2004), p. 23
I've never climbed Mt. Fuji, but I can well imagine the female voice recording familiar to every train passenger in Japan telling the pilgrims as they approach the torii of their impending arrival at the summit, thanking them for having climbed up, and asking them to mind their magokoro 'truehearts' instead of their ashimoto 'footsteps' as they pass through the torii: 間もなく山頂に到着いたします。ご乗山真にありがとうございました。鳥居を通るとき真心にご注意願います。(Mamonaku sanchou ni touchaku itashimasu. Gojousan makoto ni arigatou gozaimashita. Torii o tooru toki, magokoro ni gochuui negaimasu.)
And then telling them where to find the toilets and vending machines.