Haven't played yet but the overview has a few oddities that could be clarified.
He suddenly finds a robot (automaton) that looks like a girl, but it is broken
To me it would sound better if it was, "He suddenly finds a broken robot (automaton) that looks like a girl."
Also, most people know that an automaton is basically just a robot so you could probably leave the word robot out.
The main character will have to repair the automaton and face the problems that she brought herself.
This makes it sound like the main character is female. (Once again, I have not played it yet but the tag says 'male protagonist')
The story of a guy who lives with his sister without parents.
The start of the sentence doesn't quite flow here. Something like: "This is the story of..." or "This game/story follows a guy who...".
And finally, 'whithout parents' is somewhat unclear. Are they orphaned? Have they moved away from home? Are their parents alive but unable/unwilling to see/take care of their children? It's just a little vague.
Now that I have played it a bit, it seems quite likely that you are not a native speaker. Either way, I recommend getting a proofreader as there are many spelling/grammer errors that a proofreader could easily help fix.