|WARNING: This article contains spoilers for the main story of OMORI.|
Mewo is a cute black kitten with white eyes and a short tail. While she is notably the first NPC encountered in the game, she only appears in three relatively minor areas: White Space, the Punishment Area in Black Space, and the Crossroads area.
In Headspace, Mewo is owned by Omori instead of Mari. According to the Omoriboy comics, she regularly comforts Omori by snuggling on him.
Mewo is seen laying down next to the floor mat, and opposite the door. Upon interacting with Mewo, she asks if you are waiting for something to happen.
Immediately after Basil's disappearance, she will instead note that there isn't much to do in White Space, before telling Omori that there's always one way to leave.
Mewo is prominently featured in the Punishment Area, the sixth room visited. Mewo will be strapped to an autopsy table, while a Butler claims that she needs punishment for "being very, very bad". If you interact with Mewo, Omori will be prompted to 'cut her open.' If he agrees, he will be asked again as Mewo grows more terrified over his intent, until he cuts her open after the seventh prompt.
Mewo does not have to be cut open; Omori can leave the room by stabbing himself after collecting the key from the Butler.
In the Real World, Mewo was owned by Mari. She is not present in reality, having apparently vanished after Mari's death, and can only be seen in a few Photo Album images. It's implied that Mari got her around the 20th of July, as Basil refers to her as "Mari's new kitten" in the photo album.
Mewo guides Sunny to his house and to Basil after Sunny's battle with Basil leaves both of them unconscious and hospitalized.
Mewo is seen twice in the photo album, both images taken on Sunny's birthday.
- White Space
"Meow? (Waiting for something to happen?)"
"Meow? (Not much to do around here, is there?)"
"Meow? (Or is there?)"
"Meow? (Are you looking for a way out?)"
"Meow? (There always is one... but...)"
- Punishment Area
"Mewo stares at you. She does not know what is happening."
"Mewo stares at you. She tilts her head out of curiosity."
"Mewo stares at you. Her eyes widen. She wants to go now."
"Mewo stares at you. She struggles to break free."
"Mewo stares at you. Her eyes are filled with desperation."
"Mewo stares at you. She tries to scream, but there is no sound."
- It's unclear what happened to Mewo after Mari's death.
- It's never stated what Mewo's breed is in-game.
- If Mewo is cut open in the Punishment Area, she will no longer appear in White Space. This can only be seen on an Omori route, as White Space is not revisited in any significant capacity on the Sunny route after Black Space.