1935-E The Buzz Messengers is the upcoming twenty-third volume of the Baccano! series.
Originally on the Dengeki Bunko website, since been taken down:
The casino party proceeds towards its climax and the fated third night. When everyone—including Firo, who is still worried about Ennis' kidnapping—gathers at the casino, the curtain rises on the final frenzied baccano—
To be released.
In September 2017, 1935-E The Buzz Messengers appeared on Dengeki Bunko's list of releases projected for a November 10, 2017 release. On October 6, 2017, Ryohgo Narita tweeted about a new personal health crisis and apologized that his novels would likely be postponed as a result. That month, Dengeki Bunko would remove 1935-E from its list of upcoming releases and issue the following apology in a footnote on its New Releases webpage: お詫び: 2017年11月に刊行を予定しておりました電撃文庫『バッカーノ！1935-E The Buzz Messengers』は、製作上の都合により発売が延期となりました。お待ちいただいております読者の皆様には、深くお詫び申し上げます。 By May 2018, that apology had been replaced with an apology for another title's delay.
In a follow-up tweet published on November 25, 2017, Narita announced that his surgery was successful, but that his subsequent recovery would slow down his writing process over the next few months. 
- Ryohgo Narita referred to 1935-E as 1935 END & EPILOGUE in his afterword for 1935-D Luckstreet Boys. No reason for the change in title has been provided by either Narita or Dengeki Bunko.
- The new title may be a reference to the jazz group The Jazz Messengers, following the trend of Baccano!'s novel titles paying homage to music bands.
- Dengeki Bunko: November new issue. Archived on September 25, 2017.
- @ryohgo_narita. (2017, October). そして小説読者の方に謝らなければならない事が……。指肘肩膝足首各所の関節痛が酷くなりまして、病院で検査したところＣＲＰが９.５オーバーで膠原病反応も出たりして色々検査する事になってしまいまして……。検査と治療の兼ね合いで各予定が少し延期になりそうです。本当に申し訳ありません……。[Tweet]. https://twitter.com/ryohgo_narita/status/916197220709416960 Accessed on December 26, 2020.
- Dengeki Bunko: New Releases. Archived on October 15,2017.
- @ryohgo_narita. (2017, November). ＰＥＴ検査で全身のリンパ節がピカピカ光っていたのでこっそり入院手術してリンパ腫摘出して検査したりしてましたが、今週悪性リンパ腫じゃないとハッキリして一気に安堵で力が抜けました。病名も確定して良性のものと解ったが、治るまでの数ヶ月やっぱり執筆ペースなどは落ちますので申し訳無いです。 [Tweet]. https://twitter.com/ryohgo_narita/status/934438623058935808. Accessed on December 26, 2020.