User blog comment:B214/Volume 22 spoilers/@comment-26345952-20160619045059/@comment-24.113.252.213-20160619184028

From what the quotes of the Gremory group (specififally Rias, Xenovia, and Asia), it almost seems like Issei will be fighting in the tornament with his own team. As in he won't be fighting as a part of Rias' team.