Premieres January 2025. There are also a bunch of character visuals and teasers you can check out in the ANN article. Synopsis from AniList:

When Sakamoto meets Aoi, the convenience store clerk, it’s love at first sight — and just like that, he retires.

Sakamoto gets married, has a daughter, opens a mom-and-pop store in a quiet town, and completely transforms … into a plus-size man. To ensure a peaceful life with his beloved family, the legendary ex–hit man bands together with comrades to face off against the looming threat of assassins.