The month of your birthday determines who your mentor will be for the Grand Magic Games:

Jan: Guildarts

Feb: Happy

Mar: Erza

Apr: Elfman

May: Lucy

June: Natsu

July: Makarov 

Aug: Mavis

Sep: Gajeel

Oct: Mirajane (ME)

Nov: Wendy

Dec: Gray

The date of your birthday determines who you will face in a Grand Magic Games fight:

1: Cobra

2: Leo

3: Eve

4: Bacchus

5: Totomaru (That fire guy from the Element 4)

6: Bickslow (ME)

7: Acnologia

8: Lisanna

9: Lyon

10: Scorpio

11: Brain

12: Minerva

13: Laxus

14: Jura

15: Ren

16: Meredy

17: Zancrow

18: Ichiya

19: Chelia

20: Capricorn

21: Hibiki

22: Midnight

23: Sting

24: Juvia

25: Rogue

26: Ultear

27: Jellal

28: Evergreen

29: Zeref

30: Kagura

31: Freed

Who is your mentor and opponent in the GMG?