Good observation. If is a retelling of the original Dracula's Curse story, Trevor and Grant would sure have to be dumb not to realize that Sypha's a woman in this one.
One of the nice things about these pachislot games is that they allow us to see attacks from camera angles and with visuals that aren't really possible in an actual action game. Well, they're possible, but they'd have to be Quick Time Events, come during a cut scene, or otherwise take a break in the action like the super attacks in Judgment.
Another Side Note:
Looking at more videos from Pachislot II. You know that little skeleton that sits on Death's shoulder in his artwork for Symphony of the Night (Death Jr.?)? It looks like you get to fight him.
パチスロ 悪魔城ドラキュラII プレミア