The soldier must have been really desperate. Suicide by grenade is a rough way to go.Not to thread jack, but here are some pictures of a bunker I visited a few years ago in Okinawa. This was one of the last bunkers to fall. Yep, there was some battle damage too.
The sign speaks for itself.
A wider view. The young man in the picture just happens to be standing and have his hands about where the Japanese soldier that pulled the pin on the grenade would have been. There were some other signs in the room that said that dozens of men died in that room before the American soldiers breached the entrances to the bunker.