As Travelers continue their journeys across Teyvat, even the most seasoned adventurers can overlook the myriad secrets woven into its landscapes. This is particularly true for the intricate web of hidden quests, elusive chests, and challenging achievements. With the grand introduction of the Hydro nation of Fontaine now behind us and the horizon holding the promise of new regions in 2026, many players are using this period of relative calm to revisit past adventures and uncover what they might have missed. The Fontaine region, a marvel of artistry and mystery, is brimming with enigmas, none more intriguing than the series of Cipher letters that ultimately lead to the hidden achievement, "The Calendar of the Future Is Longer Than the Diary of the Past."
These cryptic messages are scattered between the Liffey Region and the advanced Fontaine Research Institute. Unlike ordinary notes, they cannot be read by the naked eye; they require the specialized technology of an Energy Transfer Terminal to decipher their encoded symbols. For those looking to complete their Fontaine chronicle, here is a comprehensive guide to locating and interpreting all six Cipher letters.
Complete Guide to All Cipher Letter Locations
Finding these letters is a test of both exploration and puzzle-solving prowess. Each requires interacting with Fontaine's unique Arkhe energy system, specifically the Ousia-aligned blocks.
📍 Cipher Letter #1 - Material Office Ruins
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Prerequisite: You must first complete the "Fontaine Research Institute Chronicles" World Quest to gain access to the area.
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Location: Head inside the Materials Office ruins.
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Method: Locate the Energy Transfer Terminal on the second floor. Use it to scan and decipher the Cipher symbol located on the first floor below.
📍 Cipher Letter #2 - Academy Assembly Hall
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Fast Travel: Teleport to the northern waypoint near the Experimental Field Generator.
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Location: Make your way to the lower floors of the Assembly Hall.
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Method: You will find an inactive Energy Transfer Terminal. Hit a nearby Ousia block to activate it, then pan the viewfinder to your left to scan the Cipher letter on the wall.
📍 Cipher Letter #3 - Experimental Field Generator Area
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Fast Travel: Use the same waypoint as before.
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Location: From the teleport point, head south towards the assembly hall ruins.
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Method: Climb up to the upper floors of the structure. You will find another terminal here. Simply interact with it to scan the Cipher symbol in the vicinity.
📍 Cipher Letter #4 - Central Laboratory Ruins
This one involves a classic Fontaine energy puzzle.
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Fast Travel: Teleport to the waypoint north of the Central Laboratory Ruins.
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Location: Glide southeast towards a conspicuously ruined building.
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Method: Find the stairs leading down to the basement. Here, you'll find a locked Energy Transfer device. Use an Ousia attack to unlock it. The puzzle requires you to transfer energy from a blue Arkhe storage block to a red one. Once the connection is made, you can scan the Cipher letter.
📍 Cipher Letter #5 - Executive Office Ruins
Be prepared for a fight!
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Fast Travel: Return to the Experimental Field Generator north waypoint.
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Location: Journey west until you reach the Executive Office ruins.
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Method: Activate the terminal by striking the Energy Storage block with an Ousia attack. This will summon a group of Clockwork Meks. Defeat them to secure the area, then proceed to scan the Cipher letter.
📍 Cipher Letter #6 - Liffey Region
The final piece of the puzzle.
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Fast Travel: Teleport to the Liffey Region's Statue of The Seven.
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Location: Use the nearby stairs to descend to a lower platform.
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Method: Activate the terminal you find there and scan the sixth and final Cipher letter.
🎁 Rewards and The Hidden Achievement
The journey to collect these scattered pieces of knowledge is its own reward, but the game certainly offers tangible prizes for such diligence. Upon successfully decoding all six Cipher letters, players are immediately granted the hidden achievement "The Calendar of the Future Is Longer Than the Diary of the Past." This achievement contributes to your overall Adventurer's Handbook progress and, most excitingly, comes with a grant of Primogems—the precious currency used for Wishes.
This quest perfectly encapsulates the spirit of exploration that defines Genshin Impact. It encourages players to look beyond the main path, to investigate crumbling ruins, solve environmental puzzles, and engage with the world's deep lore. In an era where new content like the recently released region continues to expand the map, taking the time to fully appreciate the details of areas like Fontaine is a rewarding endeavor for any dedicated Traveler. So, equip your best puzzle-solving mindset, ensure your Ousia-aligned characters are ready, and set forth to claim this piece of Fontaine's hidden history. Happy exploring! 🗺️✨