That's it. Poison is reducing the HP as i walking in world map. It is not easy to running away from any kind of wolf or other at first fleeing.
Man , it was desperating. Right now , i make a new data with the same character.

I have ever succeeded in Marsh Cave at level 10 using Fighter , Black Belt , Red Mage , Black Mage before. But the data has been lost.

Maybe i was too overconfident there.
Entering the cave with a few stock of potion and antidote.
But i did teached the mage Fira , Thundara , Dia.