
I went on a trip to Japan a few months ago, and while treasure hunting in Akihabara, I found some old games from my childhood

Anyways, I just started to play the first one, I have some questions:
how can I change my main monster? the one that follows me, maybe I need to get further in the game?
The items that fall out of the grass, what do they do? I assume the coins and diamonds are money? but what are the hearts?
How can I change my ringtone? I can read Japanese so I found the Dmelo menu, but I can't seem to make it save the one I want, when I get a call it's just the normal ring..
The items I buy at the store, I know some of them evolve your monsters, but some of them give exp, how does this work?
And what is FD? i see it when I get a call from a monster, and one time it event got up on point.
Also, what are the point I get after the battle? it looks too little to be exp..
btw I heared that the games battery can die out and dlete my save.. can I do something to prevent it?
Sorry for having so many questions, it's just really hard to find info on this, though I did find some usful sits.
THanks
