The Genma are the main antagonist of all the games of Onimusha. They have different abilities, forms and weapons. There are 3 types of Genma.
Low Class: These genma are easy to kill and are not much of a problem when the numbers arent very big. these type of Genma are the most common enemies in the games.
Middle Class: These genma are normaly bigger and stronger than the rest. they weild weapons that deal a decent amount of damage per blow and also have a decent amount of resistance. The easiest way to kill one of this type is to use a magic attack (except for Onimusha 4 Dawn of dreams) and to attack them with a level 3 weapon (except in Onimusha 4 Dawn of dreams)
High Class: These type of genma are the only ones that can speak and normaly the are the bosses in all games (except in Onimusha 4 Dawn of dreams) their attacks are completely different from the rest of the enemies. A good example is the guard dog in Onimusha 3 Demon Siege. It can attack by charging against the character (Samanoske and Jacques) using lightning balls, stomping and so one also the last boss of the games normally have an 1-hit KO attack (Fortinbrass in the first game grabs the player and squizes then breathes fire and the player instantly dies) this type of genma also have the strongest attack, defence and annoying capabilites of all.