Stand by you

"Stand by you" is a visual novel that you can play it about three-five hours with no choices.
About the story
There is no one on the earth,,,,,except you and me.
One day,when KYO-YA,a high school student,woke up,the world has changed.
He can't move,buildings have gone downhill,and wast land extends.
According to a girl who passed by,it seems that the world ended.
KYI-YA,doesn't want to believe that,goes on a journey with the girl to look for other living things.
-----But.The girl had "mission".
She has to keep dying to atone human's sin.
A number of times,dozens of times,hundreds of times,thousands of times,and tens of thousands of times.She repeats to die and revive.
As KYO-YA spends time with the girl who knows only pains,he thinks he wants to make her happy.
Only him and her in the ruined world.
He goes on a journey to live with the girl who keeps to die.