Genichiro is the current leader of Ashina. When you first see him, he just looks important with his armor and his bow and his whole demeanor. He (probably) summarily kicks your ass and puts an end to the escape attempt that starts off the game.

You fight to reach the pinnacle of his castle. And as you do, you realize Ashina is weak. Its regular soldiers are thin and underfed. Their mighty gatekeeper is an old man, no longer who he once was. Its ninjas and spies just kind of idly sit on the rooftops. They're counting on a bull with flaming hay bales attached to its horns to do anything. This is no longer the mighty power that seized its own independence decades ago. The only person who seems to be worth a damn at trying to stem the bleeding is a weird guy in a mask. The first part of the game is all about fighting past everything to make it to the top of the tower of Ashina castle. This is the highest point, where Genichiro's power is centered. There he is, powerlessly begging a 12 year old to make him immortal. His only plan for if the 12 year old says no is to beg harder.

Genichiro challenges you to a fight because he wants to keep an unarmed 12 year old in his power. He still has his armor and bow but his dignified air is gone. When he's beat, he strips off his armor. He is small and lean, his skin blackened from burns. His hair is messy and unkempt. His eyes look like he's cornered and desperate.

In the same way he believes that the Ashina's traditional defenses cannot stop the country from being assimilated, he also believes that he can't win just using traditional Ashina swordsmanship. Genichiro needs heresy and mysticism. He needs immortality.

This pursuit has ruined his body and it's ruining his country. He shows you bigger tricks, but all of them have simple counters. The heretical arts aren't helping and all Genichiro feels he can do is double down on them. He's a loser.