Investigate various areas and solve riddles in a giant prison called a impregnable fortress.
Can you escape from the prison?

Story

I put myself in a giant prison to save my sister.
She has been thrown into prison for a crime she did not commit.

First prove her innocence from inside the prison,
And after that I'll escape from this prison.
That's my plan.

This prison is called 'the impregnable fortress'.

But the time has come.
Now is the time to get the escape plan to start.