Mini Castle Bleck is a castle in Into The Fourth Dimension that resembles Castle Bleck and a castle from Super Mario World that may be where D-Coins come from. When Luigi went there, he knew it was a mini version of Castle Bleck from Super Paper Mario, but found some changes, like the original Castle Bleck didn't have lava or Shark Plants (not even their normal counterparts). He found a door and entered it, then he found the D-Bully and beat him in battle, thus earning they key to the second floor of 4D Tower.
- Right turn at the lava pool with Dowser statues: Collected by Luigi
- Replica D-Star atop a Dowser statue: Collected by Mario