"That" (アレ are) is a creature of unknown origins that appeared in "Princess Secret Room".
"That" was a nameless creature that terrorized the Sasanaki Motel during Hime's group during their night stop. It has no discernible features, save for an off-grey blob-like body dotted with eyes of various sizes. It has long, spindly limbs that can twist together to form a drill-like appendage wich helps it penetrating its victims through the mouth.
In the manga, "That" apparently devours its victims from the inside which causes blood to gush out from their faces, eventually culminating in death. The people infested by the creature were oblivious of its presence until it is too late.
In the anime, the creature was sent by Zeppeli to assassinate Hime. It does not kill anyone, unlike its manga version, instead consuming their strength and forces them into a coma.
The presence of an unknown creature was first suggested when a man collapses dead in the Motel's lobby with blood coming out of his mouth, eyes, nose and ears. Hime suspected this was the doing of a monster, but remains in her room and does not tell anyone. Soon after, one of the motel's occupants was found slumped against the walls, also dead. This terrifies everyone and a few people decides to form a party to search for the unknown culprit.
During the search, one of the team's members suddenly stops when his wife starts behaving strangely. She mutters a few more words before blood starts gushing from her face like the other victims and a blob-like creature springs out from her mouth and vanishes, leaving everyone bewildered. Hiro rushes back to Hime to report the situation, but she calmly dismisses it, forcing Hiro to seek out the monster on his own.
Moments later, screamings came out from the leisure room, Hiro rushes in only to see the creature, having left its previous host, were clinging onto the arm of one of the previous victims' boyfriend. The man assures Hiro that he will be alright before "That" launches itself into his mouth. Seeing his inevitable demise, he tells Hiro to kill him along with the monster. Hiro hesitates, before Hime rushes in and stabs the man with a broken pool cue. As "That" leaps out of his mouth, Reiri comes in with a jackhammer, and Hime uses it to kill the creature.
Later on, when Hime's group is trapped inside Hiro's nightmare, "That" is seen briefly before vanishing into the shadows.
In the anime, it is instead killed by Flandre, who stepped on it and crushed it under her weight.
- The anime version changes the creature's name to "It".
- In the manga, the creature killed a total of 4 people, its final host not included, while the anime version only infested three, again not counting the final victim.