Code-scrounging anon here. To get #120, you have to:
- Get caught by Shadow Alvus in Intestines Maze. (it was somewhere around the portal to Soldier Row when I encountered it, but it can be literally anywhere since it's constantly moving)
- Get caught by Shadow Blob in Onyx Tile World.
- Get caught by Shadow Mothman at the end of Highway's top path.
- Interact with the Shadow Robot in the building that houses the Fairy effect (Onyx Tile World), or interact with the Shadow Blob while invisible. No idea why it works like that, there's no cue that anything happened, it just sets one of the switches required. It might be an oversight by the map maker.
Unfortunately, getting caught by any of those during the chasers event in Urotsuki's dream house does nothing. You have to find them in their natural habitat.