Setting from the game:

The story is set in year 2030 where an incident occur in a giant research facility called LABO which has a nuclear reactor. The incident which is the meltdown of the reactor locks everything in the facility causing 9 people, 3 rescuer and 6 people, to be locked inside it. They just have to wait to be rescued since help will come in 9 hours where the system will be recovered. The problem is...the only got magic potions (read: drugs to prevent the radiation exposure) for 6 people.

Setting in the manga:
Our main char wakes up while having 2 sexy chicks looking at him going "Are you okay, boss?". He looks at them, they seem to be wearing orange clothes but while they seem to know him very well, he doesn't remember them at all. Heck, he doesn't even remember himself. He finds out fast that they are in a facility and it's on fire. They are rescuers and need to finish their job before it's too late.
Our main char hears a girls voice and hurry to save her but as soon as she sees his face she screams "NOOoo!!", wondering what's wrong he hears a voice telling him to save her and they manage to save the girl only to find out that they have been locked inside the facility which contains a nuclear reactor. They have meds but not enough so they need to get the hell out of the facility somehow....