Seven Seas has licensed the manga, and will release the first volume in August. The company describes the series:
From the fateful moment they met to their brutal parting, the full story of Chifuyu Matsuno and Keisuke Baji is revealed at last! Racked by grief after a recent battle with Valhalla, Chifuyu receives an unexpected letter that will change everything. This spin-off series to Tokyo Revengers is currently available in English from Kodansha USA on the K MANGA digital platform. Seven Seas will publish the series in print for the first time in oversized paperbacks with new lettering, and will also release the volumes in ebook editions on other digital platforms.
K MANGA is releasing the manga in English digitally.
The manga debuted in Kodansha's Weekly Shōnen Magazine and on the Magazine Pocket app in July 2022.
Wakui launched the main Tokyo Revengers manga in Weekly Shōnen Magazine in March 2017, and ended the series in November 2022.
The manga has inspired three television anime and a new sequel is in the works. The manga has also inspired three live-action films.
Source: Tokyo Revengers: A Letter from Keisuke Baji volume 5