As soon as you enter Camp Ichigaya F1, you will notice a fire/flame seal blocking your path if you move forward. It isn’t the only route you can take, however, to get to your destination, you must pass it.
This guide teaches you how to break the seal and progress with the main story.
Getting Pass The Fire/Flame Barrier at Camp Ichigaya in SMT4: Apocalypse
For now, leave the fire/flame barrier alone as there is nothing you can do about it right now. Instead, explore the rest of Camp Ichigaya thoroughly and you should discover two new areas. One area will have Lucifuge and the next, Belial.
You must defeat these two powerful demons in battle to obtain the Seal of Rejection and the Seal of Delusion. With them, you can break the barrier blocking your path to a new area of Camp Ichigaya.