Very Difficult, but Fun.
The graphics are of course, not that good if you compare it to 2011 games. But Red Ninja was released on 2005. I can say that the graphics are pretty good if it came out on 2005. The graphics on the cut scenes are good, but not that detailed. When a character speaks, their mouth doesn't move at all. Your character Kunei is not that much detailed, it's a bit pixelated and too smooth. And if you put the camera facing upwards, you can actually see Kunei's underwear. Anyway, bottom line: the graphics are good enough for a 2005 game.
I don't get the character relationship that much because they are Japanese. The only characters I know are Shingen Takeda, and the famous Nobunaga Oda. Kunei is a ninja and she has few ninja allies. Her parents were murdered by Nobunaga and Kunei survived. Now she is off to kill Nobunaga and avenge her parents.
I made a good rating for this game because I like being challenged and it brings back the old memories on the PS2. If you like ninja's and if you like being challenged, go ahead and buy this game.