What do you mean by understand? The gameplay, or the plot? The gameplay is actually quite simple: it's just like the previous games. You can perform actions once you have sufficient bar. You defend when she does huge attacks. Your attack damage is based on bar size. Your special gauge goes up with hits on her and you, and also defended hits. Hit her head for maximum damage, hit her armor to destroy it. When she's preparing to do a real super move, she takes double damage to the head. Your best bet is to dump all your initial stat points into damage and then whallop her in the face when she tries to do a special. You get points based on how many times you defeat her, a lump based on clearing 3 rounds, how many times you cum inside of her, and how much damage you do to her in the round you lose.
The plot is basically that you're fighting in a revolution against the "empire." She is an imperial princess defending against the rebellion. You are a soldier who has already fought her before and lost. You're basically in the rebellion now to make sure you beat her.
If you get beaten by her after making her like you, the rebellion is crushed, she makes you her subordinate, and promises to help you reform the empire. If you beat her and make her your traveling waifu, the empire collapses, the two of you live happily ever after, and she's never heard from again. If you make her your slave, the rebellion wins, and you get to keep the princess as your prize for helping the revolution.
The "extra" modes are slave mode and subordinate mode. In slave, you release her from her bonds to fight her. In subordinate, she's basically "training" you. She enjoys being a slut in slave mode, and in subordinate mode, you get to give her impromptu (but well-received) hot dickings.
This is my favorite of all his works. It's just great. Simple, effective, and she's a blond, feisty princess.
