Earlier this month, it was announced that the Persona Q: Shadow of the Labyrinth manga would be published in North America by Kodansha USA next year.
Update (2016-01-26): The full English cover for Persona Q Side: P4 has been revealed by the author Mizuno Moto, and added to the bottom of this post.
Following this, the Japanese release dates for the first Persona Q manga volumes have been revealed via Amazon Japan.
The first volume of the Side: P3 manga will be published by Kodansha in Japan, through the KC DX series, and Kodansha USA in North America.
Persona Q: Shadow of the Labyrinth Side: P4
The Side: P3 manga started being serialized in Bessatsu Shōnen Magazine in February 9, 2015.
The Side: P4 manga started being serialized in Monthly Shōnen Magazine in January 26, 2015.