Nestled near the Mount Hachimantai summit in north-eastern Japan is a lake mythically believed to be the meeting place of two banished, lovestruck dragons.

Each winter, ice forms atop the Kagami Numa lake and snow piles over its frozen surface. During the spring thaw, pressure from the water’s depths causes the snow to form only in the middle of the lake, transforming the circular lake’s appearance into a giant eye with a ring of open water around its melted “pupil”. The annual phenomenon lasts barely a week between late May and early June just before the ice melts entirely.

The unique sight went viral in 2016 when a tourist took a photo of the white doughnut-shaped ring and called it the “dragon eye” on social media. Ever since, tourists from around the world have come to marvel at its translucent water.

Interestingly, dragons have long held a place in Japanese legend, and the site is said to be where a young man transformed into a dragon after drinking from a nearby pond. The love he shared for another human-turned-dragon banished to the opposite side of the mountain is believed to be what keeps the lakes in the area from completely freezing over during the late springtime. Today, some visitors even provide offerings to the dragon gods of the area.

(Video by Hiromi Tanoue , text by Yasmin El- Beih )

This video is part of BBC Reel’s World of Wonder playlist.

Join more than three million BBC Travel fans by liking us on Facebook , or follow us on Twitter and Instagram .

If you liked this story, sign up for the weekly bbc.com features newsletter called "The Essential List". A handpicked selection of stories from BBC Future, Culture, Worklife and Travel, delivered to your inbox every Friday.