User blog comment:B214/Volume 23 discussion blog/@comment-201.215.165.7-20170608162650/@comment-31137559-20170608163946

It's just the title of the DX volume which is a collection of the matches that won't appear in the main volumes. It would just be the chapter of one volume in the DX volumes. So that would be the name of the chapter in which the Issei vs Sona Rating Game.