As an Ys fan, I'm wondering if this might be a good one to TAS. Though it's probably the worst game in the series, and I've barely touched it, it looks to be pretty buggy and might provide some intresting results. Here
is a glitch I've found by holding left and right. Here it is used to get past a part of Tigris Mine that would be impossible at this point otherwise. Though it makes the background scroll and glitch, it seems that the collision stays the same, and you can glitch enemies away with this method. The only trouble is, if you go too far with it, probably if you go past the edge of the collision map, you can't use any exits and have them work.
The only thing that would make this hard/impossible is that the Ys games that I have played (1, 2, and 4), tend to make some enemies impossible to beat (as in, you do no damage), and it seems like this may be the same way. But if it could be wiggled around, maybe it would work? I haven't tried fighting any bosses or anything.
Edit: OK, it does seem like it may be the same as the other games. If it is possible to somehow get equipment quickly, it might still work, though.
Unfortunately, the guy is placed perfectly so I can't get down the ladder.