The 6 short story (originally published in DM) included in DX2 is the following:

Oppai is the Sun (Will have Poseidon appear) Student Council's Decesion (SC girl's prefference in guys will be mentioned) Let's Go with Training (It was actually this SS where the Kusangi's sword was first mentioned. Also has Saji getting totally raped by level 999999 Maous. RIP.) Worship☆Dragon-God Girl (Ophis and Kunou. The two lolis) Nekotama☆Ninja Scroll Maniac's Sanctuary (That Agares Girl appears along with her male Queen who is actually a Dragon. And her obsession with Robots and plastic models and stuff)

And also 1 new story which is LN exclusive like always. So in total 7 stories will be included.

(Info from n0m@n)