In The Legend of Zelda: Tears of the Kingdom, there are shrines that are clearly intended for players later on in the game. However, thanks to the freedom that the game provides, players are able to access any shrine if they have enough determination and creativity. The Joku-usin Shrine is one such shrine that players will find as they progress through the story, but it can be reached earlier on in Tears of the Kingdom.
Joku-usin Shrine Location in TotK
As players naturally progress through the game's story, they will eventually be pointed in the direction of the Thunderhead Isles in the Faron Grasslands Sky. This floating collection of islands can be accessed with the help of the Popla Foothills Skyview Tower.
After being launched into the skies, players should make their way south toward the tips of the isles. If players have not completed the story quest "Secret of the Ring Ruins," they will have very limited visibility in the Thunderhead Isles due to the overwhelming storm cloud. However, this guide will later advise determined players on how to reach the shrine despite the hindrance.
Players should navigate the isles using the Ascend ability, a couple of rails, and some skillful jumping. For players with full visibility, the path ahead is quite straightforward. As players approach the coordinates 1142, -3329, 0762, they will find a workstation of sorts next to another rail.
Players should assemble a makeshift cart to proceed down the rail until they are directly under the higher island. Once underneath, players can use Ascend to enter a chamber within the island housing the Joku-usin Shrine.
Joku-usin Shrine Walkthrough (Proving Grounds: Short Circuit)
Upon entering the shrine, Link will be stripped of all weapons and armor to prove his worth with the items provided. In this challenge, Link must defeat six first-level Soldier Constructs and one Soldier Construct III. Although the shrine encourages the use of electricity to harm the constructs, any damage will work.
Players should pick up the two sticks near the door and rush to the back of the room, where they will find a powerful Shock-Emitter to fuse with their weapons. After dispatching the Zonai constructs, Link can enter the final room to receive an 
Electro Elixir from the chest and a Light of Blessing from the statue.
How to Get to Joku-usin Shrine Early
Players that wish to reach Joku-usin Shrine before the intended time are at full liberty to do so. The Popla Foothills Skyview Tower can still be used to reach the Thunderhead Isles, but with the limited visibility upon landing, players must be ready for a difficult venture.
No light sources are able to improve visibility for the player, including Zonai Lights and Brightblooms. The best tools for navigating the isles and locating solid ground are watching for where lightning strikes, spotting the red glow of constructs' eyes, or throwing/shooting objects out in front of Link.
If players look at their map fully zoomed in, they should be able to faintly see the outlines of the isles behind the dark storm cloud to roughly guide them.
Unfortunately, with the shrine being located within an island, players are not able to simply build and pilot a flying machine directly to it. Players should strive to reach the rail and work station around 1142, -3329, 0762 by either flying there or navigating on their own. After reaching the coordinates, players should assemble a makeshift cart as described above to progress down the rail until they can ascend into the shrine's chamber.
The Legend of Zelda: Tears of the Kingdom is available for the Nintendo Switch.