Under Mythos Announced for 2028, Combining Hot Spring Inn Management, Extraction and Dark Fantasy JRPG

Under Mythos has been officially announced as KADATH's first project, introducing a dark fantasy JRPG that combines peaceful life at a mysterious hot spring inn with dungeon exploration, extraction systems and action-based combat. The game was unveiled on September 10, 2026 and is currently planned for release in 2028.

Players follow a lone cat that wanders into another world while searching for Mother. It eventually discovers a strange inn where inhabitants of the other realm come to relax, beginning a seemingly gentle new life that gradually shifts as the familiar world becomes increasingly unpredictable and consumed by madness.

Quick Summary

• Title: Under Mythos
• Japanese title: アンダー ミュトス
• Format: video game
• Official genre: dark fantasy JRPG
• Game system: hot spring inn management simulation × extraction
• Developer: KADATH Co., Ltd.
• Publisher in press release: TBD
• Current Steam publisher listing: KADATH Co., Ltd.
• Platform: PC
• PC store: Steam
• Platform: Nintendo Switch
• Dedicated Nintendo Switch 2 version: not announced
• Release window: 2028
• Specific release date: unannounced
• Price: unannounced
• Players: 1
• Protagonist: a lone cat
• Initial story objective: searching for Mother
• Major location: a mysterious hot spring inn in another world
• Inn guests: inhabitants of the otherworld
• Inn activity: welcoming and serving guests
• Dungeon objective: gathering food and resources
• Combat: action-based
• Enemies: beings transformed into grotesque forms
• Extraction: return safely with dungeon resources
• Progression: gathered resources feed back into inn development
• Inn development: creates new encounters and experiences
• Loop: inn → dungeon → resources → development → further exploration
• Core contrast: comfort and madness
• World progression: peaceful life gradually gives way to unpredictable madness
• Character design: Atsuko Nishida
• Scenario: Takumi Miyajima
• Music: Noriyuki Iwadare
• Producer: Yoichi Miyaji
• Atsuko Nishida: known for work on various Pokémon designs
• Design inspiration mentioned by Nishida: Nyarlathotep from the Cthulhu Mythos
• Lore distinction: the protagonist has not been confirmed to literally be Nyarlathotep
• Takumi Miyajima: known for work including Tales of the Abyss
• Noriyuki Iwadare: known for GRANDIA, LUNAR and Ace Attorney
• Yoichi Miyaji: producer associated with RPGs including LUNAR and GRANDIA
• KADATH founded: January 2026
• Under Mythos: KADATH's first project
• Development status: preparing production of a vertical slice
• Vertical-slice purpose: establish visual, audio and gameplay direction at intended final quality
• Collaboration partners: currently being sought
• Announced language: Japanese
• Announced language: English
• Announced language: Simplified Chinese
• Announced language: Traditional Chinese
• Announced language: Korean
• Indonesian: unannounced
• Steam App ID: 5155220
• Steam wishlist: available
• Teaser trailer: released
• Current footage: work in progress

Teaser Trailer, Steam and the World of Under Mythos

A Cat Searching for Mother Finds an Inn in Another World

Under Mythos begins with a remarkably simple motivation: a lone cat is searching for Mother.

That journey takes the cat into another world, where it discovers a mysterious hot spring inn used by the realm's inhabitants as a place to rest.

Hoping to reunite with Mother someday, the protagonist begins working there and welcoming its unusual guests.

This is the “comfort” side of Under Mythos. The cast is deliberately charming, the inn provides a relatively peaceful everyday setting, and developing the establishment becomes an important part of progression.

The calm is deliberately designed as a contrast, however. As the story progresses, the once-familiar world begins changing in unexpected ways and moving toward the “madness” that defines the other half of the game's identity.

Inn Management and Dungeon Exploration Feed the Same Loop

Under Mythos does not treat management simulation and dungeon exploration as unrelated activities.

Serving the inn's guests requires food and resources, sending players out into dungeons across the otherworld to gather what they need.

Exploration eventually leads into action combat against entities that have transformed into grotesque forms.

Defeating enemies is not the only objective. Players also need to make it back safely so the food, materials and rewards collected during the expedition can actually be used.

Those resources are then reinvested into the inn. Developing the establishment creates new encounters and experiences, which in turn leads back into further exploration.

The resulting loop moves continuously from the inn into dangerous expeditions and back again.

KADATH officially uses the term “extraction” for this structure, although exact penalties for failure, resource loss, inventory rules and the detailed structure of individual runs remain unannounced.

A Cute World Gradually Slips Into Madness

One of the clearest ideas in the teaser is the contrast in tone.

Under Mythos initially presents expressive, cute characters, food, a hot spring inn and everyday scenes that feel deliberately comforting.

That atmosphere eventually collides with dungeons, grotesque creatures, abnormal behavior and imagery that is significantly more disturbing.

Composer Noriyuki Iwadare has also offered a useful clue about how the transformation affects the soundtrack. He described working through the problem of expressing the protagonist's sudden turn toward madness, using a musical shift from lightly Japanese-flavored material toward high-speed jazz.

That suggests the transformation is not limited to narrative and visuals. Music is also expected to evolve alongside the protagonist.

The actual cause of the madness, the nature of the otherworld, Mother's connection to the larger conflict and the full extent of the horror elements have not yet been revealed.

Atsuko Nishida Reinterprets Nyarlathotep Through Character Design

Among the most notable creators involved is Atsuko Nishida, a graphic designer and illustrator known for work on numerous Pokémon designs as well as card illustrations and corporate characters.

For Under Mythos, Nishida specifically identified Nyarlathotep from the Cthulhu Mythos as an inspiration behind her interpretation of the character design.

Her stated goal was to turn the god of chaos into a character that could feel lovable and familiar, closer to an everyday cat.

That comment helps explain how Under Mythos can place cute character design beside its title, horror imagery and gradual descent into madness.

There is still an important distinction between design inspiration and confirmed lore. Nishida's statement does not yet establish that the protagonist is literally Nyarlathotep within the story or that Under Mythos will directly adapt Cthulhu Mythos canon.

For now, Nyarlathotep is confirmed as part of the creative design reference.

Veterans of Tales of the Abyss, GRANDIA and LUNAR Join the Project

Under Mythos also brings together creators with substantial JRPG experience.

Takumi Miyajima handles the scenario and is known for writing work including Tales of the Abyss.

Music is composed by Noriyuki Iwadare, whose extensive credits include the GRANDIA, LUNAR and Ace Attorney series.

Yoichi Miyaji serves as producer, carrying a career closely associated with RPGs including LUNAR and GRANDIA.

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Their experience forms an important part of the project's foundation: a traditional understanding of JRPG storytelling combined with a structure built around inn management, extraction, action combat and dark fantasy.

Under Mythos is not a continuation of any of those earlier franchises. It is a new original IP being developed as KADATH's first project.

KADATH Is Still Preparing the Vertical Slice

Despite the trailer, screenshots, Steam page and 2028 target, Under Mythos remains relatively early in production.

KADATH says the project is currently preparing production of a vertical slice.

That prototype is intended to demonstrate the visual and audio direction as well as core mechanics at a quality level representative of the eventual finished game.

The company is openly seeking collaboration partners for vertical-slice production and future development.

KADATH itself was established by Yoichi Miyaji in January 2026 with a mission centered on creating globally loved characters and IP while developing JRPGs with deep narrative experiences.

It also names support and cooperation from domestic and international developers including Matrix, Liz, Cosmo Machia and Taiwan-based iSWEETY.

That early production status matters when interpreting the material currently shown. The announcement explicitly notes that its game footage and screenshots remain in development.

Publisher, Price and Exact Release Date Remain Open

The currently announced platforms are PC via Steam and Nintendo Switch.

The release target is 2028, but no specific month or day has been announced.

A dedicated Nintendo Switch 2 edition is likewise unannounced. The platform announcement specifically names Nintendo Switch, so a separate Switch 2 release should not be assumed until KADATH confirms one.

There is also a small metadata discrepancy.

The press release says the publisher remains undecided, while Steam currently lists KADATH Co., Ltd. in both its developer and publisher fields.

Because KADATH is still seeking collaboration and publishing partners, the final publishing arrangement should be treated as unsettled until a later announcement clarifies it.

Price, editions, physical availability, age rating, preorders, demo plans, voice cast and a precise release date also remain unannounced.

Why This Matters

1) Management and extraction directly reinforce each other

Dungeon resources have a purpose beyond the expedition itself because they are brought back to the inn and used to unlock the next stage of progression.

2) Cute and horror are designed as two sides of the same world

The comforting hot spring routine establishes normality before the environment and characters begin slipping toward madness.

3) Nyarlathotep receives an unusual visual interpretation

Atsuko Nishida translates inspiration from the god of chaos into a cat-like character designed to feel approachable and lovable.

4) Veteran JRPG creators are experimenting with a different structure

Experience connected with Pokémon, Tales of the Abyss, GRANDIA and LUNAR is being applied to an original IP that combines action combat, extraction and inn management.

Game Information

For now, the additional important information currently known includes:

• Under Mythos is a new original IP
• it is the first project from KADATH
• KADATH was established in January 2026
• Yoichi Miyaji founded the company and serves as producer
• KADATH's mission includes creating globally recognized characters/IP and story-driven JRPGs
• the story begins with a cat searching for Mother
• the cat wanders into another world
• it discovers a mysterious hot spring inn
• otherworldly inhabitants visit the inn to rest
• the protagonist begins working there while hoping to reunite with Mother
• peaceful everyday life gradually transforms into madness
• dungeons provide food and resources for the inn
• dungeon exploration includes action-based combat
• enemies can appear in grotesque transformed forms
• expedition resources need to be brought safely back to the inn
• resources are reinvested into inn development
• developing the inn can open new encounters and experiences
• the official game system is described as hot spring inn management simulation × extraction
• exact extraction-failure penalties remain undetailed
• inventory and resource-loss rules remain unannounced
• Atsuko Nishida handles character design
• Nishida cited Nyarlathotep as a design inspiration
• the protagonist's literal identity as Nyarlathotep is not confirmed
• Takumi Miyajima handles the scenario
• Noriyuki Iwadare composes the music
• Iwadare described shifting from Japanese-flavored music toward fast jazz to represent the protagonist's madness
• Yoichi Miyaji serves as producer
• the game is planned as a single-player title
• PC and Nintendo Switch are the announced platforms
• the Steam App ID is 5155220
• Steam wishlisting is available
• the release target is 2028
• a precise date remains unannounced
• price remains unannounced
• a physical edition remains unannounced
• preorders remain unannounced
• no public demo has been announced
• an age rating remains unannounced
• the voice cast remains unannounced
• Japanese support is announced
• English support is announced
• Simplified Chinese support is announced
• Traditional Chinese support is announced
• Korean support is announced
• Indonesian support has not been announced
• Steam currently lists Windows 11 64-bit as the provisional minimum OS
• the provisional minimum CPU is an Intel Core i5-10400 or AMD Ryzen 5 3600
• provisional minimum memory is 16 GB RAM
• the provisional minimum GPU is an RTX 2060 or Radeon RX 5600 XT
• provisional storage is 20 GB
• Steam states that these requirements may change during development
• the project is currently preparing a vertical slice
• the vertical slice is intended to demonstrate visuals, audio and mechanics at the planned final quality
• KADATH is seeking collaboration partners
• the press release lists the publisher as TBD
• Steam currently lists KADATH Co., Ltd. as publisher
• all currently shown announcement screenshots are marked as work in progress
• official information is available through the Under Mythos Official Website
• official updates are available through Under Mythos Official X
• the teaser is available through the Under Mythos Official Teaser Trailer
• the PC version can be wishlisted through Under Mythos on Steam

Closing

Under Mythos introduces KADATH with an unusual mix of comforting hot spring management, dangerous resource-gathering expeditions, grotesque action combat and a cute world that gradually descends into madness. Its experienced creative staff gives the project strong JRPG roots while its extraction-management loop pushes the structure in a different direction.

The game is targeting a 2028 release for PC and Nintendo Switch, but development is still approaching its vertical-slice phase. Pricing, a precise launch date, the final publisher, rating, voice cast, editions and many details surrounding combat and extraction all remain to be announced.