Due to platform rules, I cannot embed direct clickable links, but here are the exact search terms for DLsite (as of 2026):
Pro tip: Wait for DLsite’s "Doujin Game Festival" (held every March and September). Both the base game and DLC are typically 30-40% off during that period.
Previous fan patches were rough. The DLC offers a complete, human-translated script by a credited localization team. Nuances, double-entendres, and spy jargon are preserved. Over 200,000 characters of Japanese dialogue have been converted.
Q: Does this work on the Steam version of Agent Sirius?
A: No. Agent Sirius is not officially on Steam. This DLC is exclusively for the DLsite version. Pirated copies will crash due to DRM checks.
Q: Do I need to finish the base game first to use the DLC?
A: No. You can install the DLC immediately and play from the start in English. The epilogue only unlocks after completing any main ending. eng agent sirius dlc rj388166 rj01259073 new
Q: Are there adult scenes in the DLC?
A: Yes. The DLC does not censor content. All 14 original H-scenes remain, plus 1 new animated scene in the epilogue. All are mosaiced as per Japanese law.
Q: The "new" label – does that mean another update is coming?
A: The developer announced on Ci-en (December 2025) that Version 2.0 is the final update. "New" refers to the DLC’s release status as of early 2026.
The world of adult visual novels and RPG doujin games has seen a sharp rise in high-quality, lore-rich titles over the past few years. Among the standout titles is the original Agent Sirius, a game that captured audiences with its spy-thriller narrative, intricate relationship mechanics, and high-stakes decision-making. However, for English-speaking fans, there has always been a barrier: language.
Enter the ENG Agent Sirius DLC, cataloged under RJ388166 and RJ01259073. With the "new" updates rolling out, this long-anticipated localization and expansion pack has finally arrived. But what exactly is included? Is it worth the reinstall? And how do these two product codes work together? Due to platform rules, I cannot embed direct
This article covers everything you need to know about the new English DLC for Agent Sirius.
Agent Sirius is a mystery RPG developed by Kumada Gaon that follows the story of Beni Akesuzu, a high school detective who is also a secret agent for an organization specializing in the supernatural. Game Overview
The game is set at Star Haven High School, where mysterious incidents targeting female students have begun to unfold. Players take on the role of Beni, alongside her friend Nadeshiko, to investigate these events. Genre: Mystery RPG / Investigation.
Core Mechanics: Exploring the campus, gathering clues, solving puzzles, and battling supernatural foes hiding in the shadows. Pro tip: Wait for DLsite’s "Doujin Game Festival"
Story: Beni works for "Bancho," a secret organization dedicated to fighting monsters that aim to brainwash the school's population. DLC & Updates
The specific identifiers RJ388166 and RJ01259073 refer to product codes on platforms like DLsite, typically indicating localized or expanded content versions.
Recent Activity: A significant update (Build 22740810) was recorded on SteamDB as recently as April 11, 2026.
System Requirements: The game requires Windows 7/8/8.1/10, 4 GB of RAM, and approximately 1 GB of available storage space.
Availability: You can find the game and its related content on platforms like the Steam Store or specialized retailers like the Saikey Store. Agent Sirius Patches and Updates - SteamDB