Shueisha Games Launches Steam Demo for Hon to Kagi no Kisetsu, Covering Chapter 1 in Full
The demo lets players work the Chapter 1 safe mystery themselves as Horikawa, so even readers who know Yonezawa's novel have an experience the book cannot give them.
Key Facts
- Shueisha Games released the Steam demo for Hon to Kagi no Kisetsu on October 20, 2026, the first day of Steam Next Fest.
- The Hon to Kagi no Kisetsu demo includes all of Chapter 1, "913," in which Mari Uragami asks Jiro Horikawa and Shimon Matsukura to open her late grandfather's safe.
- Hon to Kagi no Kisetsu is planned for release this winter on Nintendo Switch and Steam, developed by iMel and published by Shueisha Games.
- Kazuki Ura voices Jiro Horikawa, Yuichiro Umehara voices Shimon Matsukura, and Arisa Sakuraba voices Mari Uragami in Hon to Kagi no Kisetsu.
- Shueisha Games says the Library Committee Series, which begins with Honobu Yonezawa's Hon to Kagi no Kisetsu, has passed 400,000 copies in cumulative circulation.
Reporting from 2 sources: 4Gamer.net, ASCII.jp.
Shueisha Games released a Steam demo for the adventure game Hon to Kagi no Kisetsu on October 20, 2026, the opening day of Steam Next Fest. The demo contains all of Chapter 1, titled "913." Developer iMel is handling the game, which is planned for release this winter on Nintendo Switch and Steam. Hon to Kagi no Kisetsu adapts Honobu Yonezawa's novel of the same name, published by Shueisha Bunko. It follows Jiro Horikawa and Shimon Matsukura, two high school boys on the library committee who take on mysteries that arrive in their ordinary lives. In Chapter 1, senior student Mari Uragami asks the pair to open an "unopenable safe" left behind by her late grandfather, and the grandfather's words serve as the clue. The game uses illustrations and full voice acting throughout, and in some scenes the player solves the mystery directly as Horikawa. Kazuki Ura voices Horikawa, Yuichiro Umehara voices Matsukura, and Arisa Sakuraba voices Uragami.
Shueisha Games timed the demo to Steam Next Fest, which opened on October 20, 2026 at 2:00 JST. The company also published a demo digest video for players who cannot run the build, showing the story's opening and the game's atmosphere.
The game carries Japanese, English, Traditional Chinese, and Simplified Chinese language support. It is a single-player title. Publisher and copyright lines list iMel alongside Shueisha and Honobu Yonezawa.
The source novel is the first entry in Yonezawa's Library Committee Series, which has passed 400,000 copies in cumulative circulation. A second installment, Shiori to Uso no Kisetsu, is also on sale. Yonezawa won the 166th Naoki Prize and the 22nd Honkaku Mystery Grand Prize in 2022 for Kokurojo.
iMel develops with Artemis Engine, a multi-platform engine built for novel and adventure games. Its prior work includes development on Tanetsumi no Uta and Lilac, plus port development for Stella of The End and ATRI.
The character notes describe Horikawa as trusting and often asked for favors, but with sharp insight. Matsukura is cynical and mature in his thinking, and stands out for his height and looks. Uragami is a third-year student and former library committee member with slightly sleepy eyes and a mischievous smile.
Synthesized by Yomimono from the 2 cited sources below, including Japanese-language reporting where cited, then editorially reviewed before publishing.