Nikkō: Strata of a Landscape — The Mountain of Gods and Buddhas, the Lake That Had No Fish
But geography alone doesn't fully account for it. "Fish cannot ascend naturally" and "people do not bring fish up" are two different things. For a fisherman, the first is obvious; the second demands an explanation.
Tennō II: Two Basins - The Imagination of Governance
If the question is how the Emperor came to occupy the position he did — not as the strongest ruler, but as the center of an order that outlasted every ruler — the entrance to that question is not Kyoto. It is Nara.