Archers are a very useful part in any army. You need them to soften up the enemy before he arrives, and to try and get rid of those excellent hand-to-hand combat troops. They do not need direct line of sight to fire, so can shoot over hills (unlike gunpowder troops). When given a hilltop, they can shoot further and increases the damage caused by the arrows. They are vulnerable to cavalry charges, so keep a unit of Yari Samurai behind them to ward of this threat. Remember that they do run out of ammo, but when they are all otu they are not useless. They can beat Yari Ashigaru in a straight fight, and stand a pretty good chance against yari samurai if given a small advantage (a hill, or being less tired).
Attack Factor 0
Defence Factor 0
Armour 1
Morale Bonus 0
Walk Speed 6
Run Speed 10