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Yoku
September 17, 2026 at 03:32 AM
Added 3 gameplay images (2026-09-16)
Yoku is the in-run resource of dungeons in Soulbound: Online. It drives the relic system inside a run. It was also once an energy cost you paid to open reward chests, and that part of the mechanic has since been removed from the game.
As you defeat enemies and clear objectives inside a dungeon, Yoku crystals drop and fill your relic experience bar. Each time the bar fills you choose one of three relics to add to your build. In that sense Yoku is the relic experience of a run: more Yoku means more relic picks and deeper synergies before the run ends. Which relics you are offered is shaped by your equipped weapon and abilities and by the upgrades you have already bought.

Yoku used to double as a third energy bar alongside health and stamina. Opening a dungeon's reward chest cost Yoku energy, scaling with difficulty, and the pool refilled daily and could be topped up through contract rewards and consumable items. That cost has been removed: dungeon chests are now claimed for free, and there is no daily Yoku allowance to plan around. Older guides that tell you to ration Yoku between chest openings describe a version of the game that no longer exists.
Several item names, weapons, tools and even a building still carry the word. They are ordinary materials and equipment with nothing to do with the retired energy bar, and they are listed further down this page.

Rare Yoku can be refined at the Chemistry Lab among your crafting stations, tying the dungeon resource back into base crafting and the wider economy.
Health and stamina are the two energy types the Early Access build actually tracks. Stamina is spent on gathering, at three points per action, and refills passively over time.

The word turns up on materials, weapons, a fishing tool, an event fish and a building. The Yoku Forge sits in Arcadia next to Dr. Fritz's Lab, most of the refining happens at the Chemistry Lab, and the data drops come out of the hacking nodes covered on Life Skills.
Name | Type | What It Is |
|---|---|---|
Yoku Forge | Building | A building in Arcadia where the vendor Yoshimoto sells apartment crafting stations and furniture |
Yoku Shard | Material | A crystalline shard used in Yokulite, Fuel Burner and Transmutation Matrix recipes |
Yokulite | Material | Crafted from Yoku Shard and Synth-Fluid, then used across armour, weapon, furniture and elixir recipes |
Yoku catfish | Fish | A catch refined into Yoku Scale |
Yoku Scale | Material | Refined from Yoku catfish at the Chemistry Lab, and used in Voltscale gear recipes |
Yoku Fillet | Material, Tier 4 | Made from Yoku Salmon at the Chemistry Lab, and used in Tritanium gear recipes |
Viridium Yoku Fillet | Material, Tier 5 | The separate tier-five fillet that Gearforge recipes call for |
Celestial Yoku Staff | Weapon, Tier 6 | Recorded with the greatsword subtype in the item data despite its name, and the Lunar set's only greatsword. Patch 4 made crafted copies match their dropped versions instead of rolling different primary stats |
Viridium Yoku Staff | Weapon, Tier 5 | The Lunar staff one tier below the Celestial version |
Viridium Yoku Hammer | Weapon, Tier 5 | A Lunar hammer from the same tier-five line |
Finnley's Yoku Magnet | Fishing tool | An upgraded version of the fishing magnet Finnley gives you. Patch 4 set it to boost fishing accessory table chances by 2.5% over the standard version |
Infused Yoku Chum | Fish | A fish caught at the Blackwake fishing spot off Neo-Tilus and handed back to their vendor for event chests, rather than anything you put on a hook. Patch 3 fixed it disappearing after being moved out of the bank |
Yoku data chunks | Hacking drop | Pulled from Large Lockboxes, and one of the sources of Hacking XP |
There are three Yoku fillets, one for each of the top gear tiers, and they are not interchangeable. The plain Yoku Fillet is the Tier 4 item, mixed from Yoku Salmon at the Chemistry Lab at Chemistry level 4. The Viridium Yoku Fillet is the separate Tier 5 item. The Celestial Yoku Fillet is the Tier 6 one, mixed at Chemistry level 24 and called for by Gearforging 50 recipes. Every recipe wants the fillet from its own tier, so a Gearforge recipe refuses a fillet from the tier below no matter how many you are carrying.
Refining them is one of the slower jobs left in the game. A Yoku Fillet takes twenty-six minutes and fifteen seconds at the Chemistry Lab, and a Celestial Yoku Fillet takes about an hour and a half.
The Viridium version was missing from some chemistry stations for a while. Patch 3 brought it back and made Gearforge recipes recognise it correctly.
If a recipe refuses the fillet sitting in your bag, check the tier on the tooltip before assuming the recipe is bugged.