Purchasing this item will add Mario as a playable character and the "Actions in the Lower World" selectable stage in MELTY BLOOD: TYPE LUMINA.

Mario Downloadable Content set contents
① Mario Playable Character
② Mario story
③ "Actions in the Lower World" stage
④ Mario network avatar, custom icon, plate, title, and gallery item

More details on the official game page of DLC: Playable Character - Mario ...