MELTY BLOOD: TYPE LUMINA

The way to obtain illustrations is as follows:
Play Count. Complete Story, Score Attack, Time Attack and Survival Mode counts for those.
Story Clear Count. Complete Story mode.
View Scene - EX Special. You get this one after watching specific character perform a EX Special move (even if you are not controlling it).
View Scene - Arc Drive. You get this one after watching specific character perform a Arc Drive move (even if you are not controlling it).
View Victory Demo. You get this one after watching Victory scene for specific character (even if you are not controlling it).

The two we're interested in are 'View EX special' and 'View Arc Drive'.
First off, go through and claim all of the illustrations you've already earned this way, as even seeing the cpu or another human do the required moves unlocks the achievement for you as well.
After you've done most of the other achievements (to cut down on grinding), claim all of the illustrations that you've earned, then go into training and do the 'Last Arc' combo mission. Do the last arc and then do arc drive and a few special moves that use the B button (B on the controller, C in game) as sometiems what gives you the "Ex special" is different. Then claim the two illustrations and repeat for up to 14 other characters depending on how many you've already done

PS: Hitting 'character select' when in the missions will put you into mission mode for real and you have to go through more menus to get back, but hitting 'return to single play' will take you directly to the menu you were at before