[supernoob]

after he broke the wall why didnt he leave with shiro?
i think the other people left
so how come hes still there
and why didnt anyone else leave when they had the chance?

[Murderality]

Well I imagine it's because the group that left only had enough candies to sustain a few people for an extended period of time (Remember there collars inject a dose of posion into them every day) also Ganta probably didn't want to leave Shiro and co. behind. Plus there's the fact that he's still wanting revenge against Red Man.

[laccone94]

I think it was due to him having unfinished business... he still needs to figure out who the red man or rotton egg is. i think it mentioned it but i dont rember

[K3pToK]

Originally Posted by supernoob

after he broke the wall why didnt he leave with shiro?
i think the other people left
so how come hes still there
and why didnt anyone else leave when they had the chance?

He couldn't leave through the hole for a number of reasons:

1) His collar thing is constantly injecting poison into his body. Unless he takes the collar off, Stockpiles candy's, or builds up an immunity, he's stuck there.

2) He has more friends there. The brother/sister peeps there couldn't escape because of collar poison too, and they wouldn't be able to get to the hole anyway because of its location.

When the other dudes left, I believe they still had there collars on, so my theory is:

1) That they removed collars somehow and are living in secret, or...

2) They lived long enough to get the Flash Drive with the data to the outside world, relocate to a secret location, and die.

The reason no one else left through that hole is probably because the psycho director didn't want any of his toys to escape, so he barred entrance to it and quickly sealed it up.