Survival: Shounen S no Kiroku

Survival: Shounen S no Kiroku (サバイバル～少年Sの記録～) is a manga written by SAITO Takao and illustrated by MIYAGAWA Akira.

Plot
Could you survive in the wilderness that has lost all civilization? A huge earthquake occurs while Satoru and his friends are exploring a cave. After somehow making it to the surface, Satoru is shocked by the scene that lays before his eyes. From that day on, the lonely battle for survival begins!