So I'm on May 3rd of the last route, got a short scene with Takeshi before jumping back to "Kid" who went with Sara to look in the mirror more calmly.
I know all seven living people now, finally. Finally finally.
There are two kids.
I will name them Kid A and Kid B.
You see Kid A when you play as Takeshi, he is the guy in OP as well.
Kid B is more obscure, you play as him when you do You's and Sara's route but you can't see him thanks to how the VN functions. He has blonde hair and if you're clever you'll realize he looks nothing like Kid A in You's and Sara's ending CGs.
So to organize this.
When you play as Takeshi (Tsugumi & Sora) you have Takeshi, Tsugumi, Sora, Kid A, and Coco with you.
When you play as Kid B (You & Sara) you have Takeshi, Tsugumi, Sora, Kid B, and Sara with you.
Sara, Coco, and Kid's A & B are the anomalies.
Somehow, I can't tell yet, these four people are never together. Sara swaps with Coco and Kid A swaps with Kid B. So Coco and Kid A are connected while Sara and Kid B are connected. Sara and Kid B are siblings after all.
The strangest part is that Kid B thought he looked like Kid A. Thanks to the fact LeMU only has one mirror in the whole freakin' place he never saw his own face and assumed it look like Kid A it seems.
Kid B looks older too, Kid A is the real mystery now honestly...
Oh and I should list people's connections with LeMMITH:
Sora - AI of insell null, runs everything in LeMU, gets suspicion for knowing probably everything but not telling us.
Tsugumi - immortal(!) paranoid girl who was researched on before, seems to understand that something really not right is happening. As in, getting stuck here was not a coincidence and she might even know about the infinity loop. Has a pet rat hamster.
You - father disappeared, mother died 17 years ago. Apparently she still has a mother though, we see her at the end of You's route. My guess? FUTURE CLONE
Sara - computer hacker, has infrared eyes, holds a pendant with an older looking guy like Takeshi, actually...it looked like Kid B. But you should be Kid B in Sara's route...siblings with Kid B at least. Huh. Researched on a lot.
Kid A - looks shrimpy, the guy you see when you're Takeshi. Kind of crazy? Can sense he's in an infinity loop sometimes.
Kid B - completely crazy, has a badass theme, siblings with Sara. Has infrared vision too, can sense he's in an infinity loop too. Was let go after Sara was a better subject in research.
Coco - pet dog Pipi, kind of just disappears everywhere in front of Kid B
Takeshi - was with Tsugumi "by chance" when the incident started, makes lots of sandwiches, gets beat up a lot, has Keiichi's VA. Least connection with everything going on so far for me.
They have that Code Geass musical that's entirely guys.