Celebi is the mythical pokemon able to travel in time... He is also nicknamed Guardian of the Forest or Spirit of the Forest (Mori no Kami 森の神). If you ever come to pray at the Ilex Forest shrine in Johto region, maybe you will have a chance to meet him...
Celebi, similar to a little fairy, is directly inspired by the kami 神, these Japanese deities. The Ilex Forest shrine is literally a Shinto shrine, and Japanese people have a habit of praying and giving offerings to the kami, invisible to humans.
In our world, Ilex Forest is located in Wakayama prefecture in Japan, south of Osaka. I was quite inspired by Koyasan town for the environment, a magnificent forest with a mystical atmosphere that I was able to visit!