There is a trick to unlock the gallery, if thats what you after. When launching game press M button on company logo screen, and the gallery will be fully unlocked
There is actually more tricks (or cheats) such as:
pressing following buttons on company logo screen will allow you to warp on any level T Simulator (tutorial level)
Y 1st stage
U 2nd stage
I 3rd stage
O 4th stage
P 5th stage
G 6th stage
H 7th stage
J 8th stage
K 9th stage
L 10th stage
And last one (not really useful imo) pressing f8 in battle will restore Main hero's health