Applicable version: updated as of 2026-10-08 (Arknights has no version-number system, so the official announcement date is used)
Arknights Yesterday's Sea Overview: What to Prepare Before Launch
Maintenance starts on October 9 at 06:00 and the event opens at 12:00 the same day, ending October 30 at 03:59 . This is a limited SideStory, so the shop closes with the event and tokens do not carry over.
The Three New Operators
The six-star Guard Clementa belongs to the Primal Guard branch, the five-star Specialist Lugu is an Alchemist, and the five-star Supporter de Toledo is a Debuffer . Save up promotion materials and LMD before launch instead of farming after the event starts.
What to Do on Day One
The order is: clear the story for first-clear rewards, unlock the event shop, then think about pulling. Arknights Yesterday's Sea event guide hinges on that first step: first-clear rewards are fixed while gacha returns are probabilistic, so take the certain payout first.
Arknights Clementa Mechanics: Why a Primal Guard Needs a Detonator
Clementa's kit revolves around Corrosion Damage. She stacks the damage onto enemies while a teammate handles the detonation, a rule that has not changed since the branch was introduced .
Why the Third Skill Is the Main Damage Tool
The third skill uses an ammo mechanic with near-global targeting and can pin down heavier enemies. In the preview the range looks narrow, so the payoff depends on whether teammates can detonate reliably.
What to Do Without a Detonator
With no detonator such as Sanguin in the squad, Clementa's returns fall well below what her panel implies. Two options: run her as pure physical burst, or park her in an auto squad for trust and wait for a detonator later. The test is simple: if detonations per run stay low, do not expect total damage near the ceiling.
Arknights Yesterday's Sea Squad Templates: Three Roles That Do Not Clash
Set up all three squads before launch so you can switch inside the event instead of reshuffling mid-stage.
| Squad | Use | Core setup | Substitute |
|---|---|---|---|
| First-clear | Clear the event story | Two Vanguards for DP, centre block, one Arts DPS at the end | Swap in a Guard for Arts |
| Farming | Repeat token and drop stages | Defender, Sniper, Supporter on auto | Use an auto-friendly Guard |
| High-difficulty | Event challenge and ambush stages | Detonator plus Clementa for Corrosion Damage | Drop to pure physical burst |
How the Three Squads Divide the Work
The first-clear squad wants a clean pass, so positioning can be conservative. The farming squad wants stability. Only the high-difficulty squad needs a ceiling push. Clementa belongs to the high-difficulty squad because her payoff shows up where burst settlement matters.
Arknights Yesterday's Sea Sanity and Shop Priorities
Natural regeneration is one point every six minutes, 240 per day, or 1680 over seven days . Every plan starts from that number.
The Seven-Day Split
| Day | Sanity | Spend on | Goal |
|---|---|---|---|
| 1 | 240 | Story first-clear | Take the fixed rewards |
| 2 | 240 | Finish first-clear | Fix positioning, do not swap operators |
| 3 | 240 | Low-tier shop plus one material sweep | Buy once-only stock first |
| 4-5 | 480 | Materials and tokens | Farm by gap, not by habit |
| 6 | 240 | High-difficulty trial | Highest trial-and-error cost |
| 7 | 240 | Clear stock | Keep a buffer for day 8 |
Which Shop Tier First
Buy the one-time tiers first, operator tokens and promotion materials, then consider unlimited LMD. Tokens do not carry over, so clear stock in the last two days .
Arknights Yesterday's Sea Practical Tips
- Spend the first 24 hours only on the story first-clear, no second runs.
- Place Clementa next to the detonator so Corrosion Damage stacks on one target.
- In high-difficulty maps, secure detonation frequency before pushing operator investment.
- Save sanity potions for the second half of the event and spend by shop gaps.
- Farm chips for the first-clear squad's gaps, not for what you might use later.
Arknights Yesterday's Sea Resource Planning: Should You Pull
Read your needs before the tier list. Without a detonator, Clementa struggles to reach her ceiling; without a Debuffer, de Toledo is the steadier pick.
| Priority | Situation | Advice |
|---|---|---|
| High | Have a detonator, lack a Guard DPS | Reasonable to pull |
| Medium | Lack a five-star Supporter, spare resources | Pick up de Toledo |
| Low | No detonator in the squad | Save for live data |
| Low | Only lack an Alchemist | Lugu is niche, skip |
The three squads compete for the same chips, so max the first-clear and farming squads first. Cross-title planning can sit alongside the guides section at gghubs.com so a single week's stamina is not spread too thin.
Arknights Yesterday's Sea FAQ
When does Yesterday's Sea start and end, and what is the compensation?
A: Maintenance on October 9 at 06:00, launch at 12:00, end on October 30 at 03:59, with the shop closing and tokens not carrying over .
How much sanity is available in the first week?
A: Natural regeneration gives 240 per day, 1680 over seven days, enough for the story first-clear plus one material sweep .
Can I still build Clementa without a detonator?
A: Yes, but the payoff drops. A Primal Guard cannot detonate on her own, so with no Sanguin-type detonator the return falls below the panel suggests; park her in an auto squad for trust first.
Should I buy sanity in the first week?
A: No. The first week lacks squad investment, not sanity, so buying near the end is better value.
Arknights Yesterday's Sea Action List
- Store the first-clear, farming, and high-difficulty squads before launch.
- Spend the first 24 hours on the story first-clear only.
- Farm materials and tokens from day 3, choosing stages by gap.
- Run high difficulty after day 6 when trial-and-error is cheapest.
- Empty the event tokens before October 30 at 03:59.