By solo... you mean only one character for entire game (exluding generations changes)? While I didn't play almost at all... no. Big no. :D It's impossible... I think even with, assuming there is something like that, NG+ and putting everything in the character, I would say it wouldn't be possible. Game is based on using the formation-focus attack. Also - lack of specific 'jobs', so to say, would also be a disaster.

Well, I just had 4 deaths in a single normal non-boss fight with full party. So perhaps you might be right.

Though I am thinking to try solo challenge myself on Hard mode of Agarest 1 to see how far I can go. I will invest only in VIT and a bit in MAG (to raise RST), and use all DEF/RST gems. And then rely on EX-Skills to kill anything, because ATK and HIT will be very low...

In case with Agarest 1, it looks to be double solo challenge, 1st part - before 2nd Gen., and 2nd part - before you get first Forbidden Tome to make marionettes. So I think to try 1st part with Leo, 2nd part with Zerva, and then with Leo again.

...but I am a bit afraid of all the grinding and I hope someone else will try this challenge :P

To be honest, first I would need to finish the game normally. :D And... with what I said - to even attempt to go solo challange you would had to have overcharged character. From the very start, cause how long could you grind on first levels? Even there you would be fast outnumbered and had to spend fortune on healing... with chance to die still.