If used in large groups; Nodachi Samurai can be devastating and can destroy a base easily; if not in heavy fire.
Mortars are devastating against Nodachi Samurai and can kill a group of them in a few hits if in the range of the impact. Spread your Nodachi Samurai around so the catapult would have to hit each Nodachi Samurai to kill it and that its impact would not affect other Nodachi Samurai as well or deploy a few heavy cavalry to destroy it.
Use ranged infantry such as arquebusiers to support Nodachi Samurai.
Nodachi Samurai can be used as a distraction for many defenses and can help protect ranged infantry such as arquebusiers from heavy fire from defenses.
The Nodachi ("large/great sword") was a Japanese two-handed, single-edged sword that could reach lengths of at least three feet, though the longest have been recorded to reach up to five to six feet in length.
Nodachi swords were so cumbersome, that the samurai wielding it either had to mount it on a baldric in the back (which prevented a fast draw, crucial in a battlefield) or simply held it and charged into battle.
Samurai carrying nodachi would be expecting to fight alone (on the ground or from horseback). These would be the most dangerous warriors on the battlefield.