Manga artist Abi (あび) has an unusual double release coming in early September. Inbi na Dōkutsu no Sono Oku de (淫靡な洞窟のその奥で) and Sōsei no Apocrypha (双星のアポクリファ) will both receive new collected volumes on September 4, 2026.
The two series come from different publishers and are at different stages of their runs. KADOKAWA's Inbi na Dōkutsu reaches Volume 10, while Abi's original Kodansha manga Sōsei no Apocrypha moves into Volume 4.
> Light spoiler notice: This article references story developments included in the official synopses for Volume 10 and Volume 4 without revealing how their major conflicts are resolved.
Quick Summary
- Manga artist: Abi / あび
- Shared release date: September 4, 2026
- New volumes: Two titles on the same day
Inbi na Dōkutsu no Sono Oku de Volume 10
- Japanese title: 淫靡な洞窟のその奥で 10
- Romanization: Inbi na Dōkutsu no Sono Oku de
- Format: Manga
- Manga: Abi
- Original work: Umetane / ウメ種
- Character concept: Fufukuro / フフ黒 and Tsukineko / 月猫
- Publisher: KADOKAWA
- Imprint: Vamp Comics
- Release: September 4, 2026
- Japanese price: ¥924 including tax
- Book format: B6
- Pages: 176
- ISBN: 978-4-04-660348-7
- Series status: Ongoing
- Series circulation: More than 1.1 million copies
- Volume 10 focus: Frederica continues pursuing Alpu as the Black Ooze threat grows
- Direction: Adult-oriented dark fantasy
- Gamers Limited Edition: Newly drawn dress-up acrylic stand
- Gamers purchase bonus: Newly drawn bromide
Sōsei no Apocrypha Volume 4
- Japanese title: 双星のアポクリファ（4）
- Romanization: Sōsei no Apocrypha
- Format: Manga
- Creator: Abi
- Publisher: Kodansha
- Serialization: Yanmaga Web
- Imprint: Young Magazine KC Special
- Release: September 4, 2026
- Japanese price: ¥792 including tax
- Book format: B6
- Pages: 192
- ISBN: 978-4-06-544827-4
- Series status: Ongoing
- Volume 4 focus: The effort to save Lily and the escalating conflict in Valshura
- Story elements: Seven Calamities / Apocalypse, dragonfolk, Child of Light, and a Succubus Queen
- Gamers bonus: Newly drawn-cover four-page rough illustration collection
Covers for Both New Volumes
Two Different Series, One Release Date
Abi had already highlighted that both books would arrive on September 4.
The timing stands out because Inbi na Dōkutsu is published by KADOKAWA under Vamp Comics, while Sōsei no Apocrypha is a Kodansha title serialized through Yanmaga Web.
That gives one manga artist two tankōbon releases from two separate publishers on the same day.
Inbi na Dōkutsu Reaches Volume 10
Volume 10 marks a new milestone for Abi's manga adaptation of Inbi na Dōkutsu no Sono Oku de, based on Umetane's original work.
KADOKAWA's official synopsis places Frederica in pursuit of Alpu while the Black Ooze remains the central threat driving the dark-fantasy conflict forward.
KADOKAWA also confirms that the overall series has surpassed 1.1 million copies in circulation, giving the tenth manga volume another notable milestone.
Sōsei no Apocrypha Continues the Fight to Save Lily
Volume 4 follows Lily after she becomes the vessel of one of the powers belonging to the Seven Calamities, or Apocalypse.
Alk and his companions seek out dragonfolk living on a sacred mountain and continue training in hopes of obtaining the power of the Child of Light.
Meanwhile, the situation in Valshura escalates as Succubus Queen Rizeldia clashes with a bishop searching for Apocalypse vessels, drawing both sides closer to Alk's attempt to save his childhood friend.
Retail Bonuses Have Also Been Announced
Gamers is preparing different bonuses for the two books.
Inbi na Dōkutsu Volume 10 has a Gamers Limited Edition with a newly drawn dress-up acrylic stand, while purchases also include a newly drawn bromide subject to availability and retailer conditions.
Sōsei no Apocrypha Volume 4 receives a four-page rough illustration collection with a newly drawn cover.
Retail bonuses can vary by store and may end once supplies are exhausted.
Two Covers Highlight Very Different Identities
The Volume 10 cover for Inbi na Dōkutsu continues the darker fantasy-driven visual identity associated with the series.
Sōsei no Apocrypha Volume 4 instead centers a white-haired character against a green-and-black palette, fitting the adventure-fantasy direction of Abi's original manga.
The side-by-side release makes the visual contrast between the two projects particularly clear.
Why This Matters
1) Two tankōbon from two publishers arrive together
KADOKAWA and Kodansha are both releasing an Abi title on September 4, creating a rare double-release day for the artist.
2) Inbi na Dōkutsu reaches the Volume 10 milestone
The manga adaptation has reached double digits while belonging to a series that has surpassed 1.1 million copies in circulation.
3) Sōsei no Apocrypha continues as Abi's original series
Unlike Inbi na Dōkutsu, which is an adaptation, Sōsei no Apocrypha directly credits Abi as its creator.
Manga Information
Additional confirmed information currently includes:
- both volumes launch in Japan on September 4, 2026
- Inbi na Dōkutsu Volume 10 is published by KADOKAWA under Vamp Comics
- its regular Japanese price is ¥924 including tax
- the book contains 176 pages in B6 format
- Volume 10 ISBN is 978-4-04-660348-7
- KADOKAWA says the series has surpassed 1.1 million copies in circulation
- Abi draws the manga from Umetane's original work
- Fufukuro and Tsukineko receive character-concept credits
- the Gamers Limited Edition includes a newly drawn dress-up acrylic stand
- the standard Gamers purchase bonus is a newly drawn bromide
- Sōsei no Apocrypha Volume 4 is published by Kodansha
- the series runs through Yanmaga Web
- its regular Japanese price is ¥792 including tax
- the book contains 192 pages in B6 format
- Volume 4 ISBN is 978-4-06-544827-4
- Sōsei no Apocrypha is created by Abi
- Gamers offers a newly drawn-cover four-page rough illustration collection with Volume 4
- retailer bonuses may end when available stock is exhausted
- official Inbi na Dōkutsu no Sono Oku de Volume 10 information is available through KADOKAWA
- official Sōsei no Apocrypha information is available through Kodansha
- September scheduling is listed through the Kodansha Comic Calendar
- the Inbi na Dōkutsu Limited Edition is listed through Gamers
- the Sōsei no Apocrypha Volume 4 bonus is listed through Gamers
- Abi posts project updates through Official X
Closing
September 4, 2026 will be a double-release day for Abi as Inbi na Dōkutsu no Sono Oku de Volume 10 and Sōsei no Apocrypha Volume 4 arrive simultaneously.
Both books are already listed for preorder through Japanese retailers, with selected store bonuses also confirmed. Neither series currently has an officially announced date for its following volume.
- Abi Official X — Author Updates and Same-Day Volume Promotion
- KADOKAWA — Inbi na Dokutsu no Sono Oku de Volume 10 Release Date, Price, Pages, ISBN, Credits, and Circulation
- Kodansha — Sousei no Apocrypha Volume 4 Release Date, Synopsis, and Series Information
- Kodansha — September 2026 Comic Release Calendar and Volume 4 Price
- Gamers — Inbi na Dokutsu no Sono Oku de Volume 10 Limited Edition and Purchase Bonus
- Gamers — Sousei no Apocrypha Volume 4 Four-Page Rough Illustration Collection Bonus
