On Skycrest Island, there is an NPC quest at the top of the mountain that allows you to wish for any limited-time rods, similar to Santa's Letter. However, there is a requirement that you must complete before you can approach this NPC. So, if you are wondering what this requirement is & how to finish it, here is a complete guide to wishing in the Skycrest Event.
How to find the Ryusel NPC in Fisch

The first step in the wishing process is to reach the Skycrest Island and locate the Ryusel or Limited Time Wish Rod NPC. To do this, go to Moosewood at (350, 135, 250). Here, next to the leaderboard, you can find a large pink clam teleporter that will take you to the Fischfest 2 Island, or you can use your Magic Conch if you have completed 50% of the Fischfest 2 Bestiary. Speak with the Shipwright to take a Boat and make your way back to the Island to locate the vertical waterfall that will take you to Skycrest Island at (-25700,2591, -4712). Swim through the water to reach the top and enter the Island.

After surfacing, walk towards the left side of the Island to reach the Wish for Limited Rod NPC at GPS (-26331, 3150, -4459). Speak with him, and he will ask you to complete five trials from any single Ancient Idol.
How to complete the Fifth Trial from an Ancient Idol in Fisch
Basically, to wish, you have to complete five trials offered by any Ancient Idol on the Skycrest Island. There are seven Ancient Idols (Hayate, Ebisu, Fudo, Nagomi, Goriki, Shunsoku, Amanojaku) all around the Skycrest Island at various Locations. You can interact with them and complete all five quests offered by any of them. But I suggest you take up the trials offered by the Nagomi Ancient Idol at GPS (-26193, 3083, -4550), as it's the easiest of the seven.

Below, you can find the details about all five trials offered by the Nagomi Ancient Idol and the quickest way to finish them.
Trial 1 - Don't Move
This is the easiest quest offered to you among all the Ancient Idols. All you have to do is not move your character or camera angle for 60 Seconds.
Trial 2 - Interact with your Pet 10 Times
Another very easy trial quest: equip any of your companions from the Satchel. Then, stand in any open area along with your pet. Use the Interaction button (E) to pet your Companion a total of 10 times to finish the Trial.
Trial 3 - Catch 20 Common, Uncommon, or Unusual Fish
Equip any mid-level rod, like Rod of Depths, Fortune, Fungal, or anything of your liking. Use something like Rapid Catcher Bait until you can catch 20 fish of the mentioned rarity.
Trial 4 - Catch 100 fish using a Crab Cage
This is a time-consuming quest, but still an easy one. Go to the Moosewood Merchant and purchase 100 Crab Cages. Deploy all of these Cages along the coast of the Moosewood Dock. Wait 10 minutes, then claim the Fish or Items from them to finish the Trial.
Trial 5 - Catch 1 Grandpa Horseshoe Crab using a Crab Cage
The final and fifth Trial is to catch the Horseshoe Crab using a Crab Cage. This is a secret rarity fish available at the Desolate Deep. For this, you would need something like the Relic Crab Cage (Sunken Reliquary) or Gold Crab Cage(Tidefall Castle). After getting these good Crab Cages, place them down while using the Golden Shrimp Bait at the Desolate Deep and try to catch them under the following conditions.
- Weather: Clear, Rain
- Time: None
- Season: Spring

After finishing all five Trials, you can return to the Ryusel NPC to wish for any of the following limited-time rods.
- Acidgrinder
- Castbound
- Cinderstring
- Eardrum
- Fallen Snowblade
- Lullaby
- MiguRod
- Noiseform
- Nocturne
- Part
- Remembrance
- Soulreaper
- Steampunk Rod
- Test Rod
- Wingkeeper
- Wingripper
Remember, wishing for a limited Rod doesn't give you the Rod directly; it starts the associated quest, since these are mostly rods vaulted by the developers.
For more on Fisch, check out All Companion Locations in Fisch & How to get them or Complete Roaming Fish & Spear Hunting Guide - Fisch