It has been serialized in Shueisha's seinen manga magazine Weekly Young Jump since February 2023.

The story follows Jiro Ayasegawa, a gifted fifth-grader who joins a little league baseball team to make friends, only to be pushed toward a competitive path.

Written and illustrated by Ōhashi Hirai, The Days of Diamond started in Shueisha's seinen manga magazine Weekly Young Jump on February 9, 2023.

[3] The series is simultaneously published in English on Shueisha's Manga Plus web platform.

[14][15] The series ranked fourth in the Nationwide Bookstore Employees' Recommended Comics of 2024 list.