The 5th Shonen Jump Alpha promo has been confirmed, it is Number 88: Gimmick Puppet of Leo. To receive this card, you must purchase a membership from the Shonen Jump Alpha site.
Source:
http://shonenjump.viz.com/ygo-5th-promo
JUMP-EN064 Number 88: Gimmick Puppet of Leo Dark/Machine/Xyz/Effect 8 ATK - 3200 DEF - 2300
Effect:
3 Level 8 monsters
Once per turn, if you have no cards in your Spell & Trap Card Zone: You can detach 1 Xyz Material from this card, and if you do, place 1 Destiny Counter on this card. You cannot conduct your Battle Phase the turn you activate this effect. When 3 Destiny Counters are on this card, you win the Duel.
Ultra Rare