Just from glancing through Psy's page, she likely wins in any scenario where she leads with mind hax or power null. Kumagawa in character tends to screw around with his opponents before going for anything conclusive, and usually likes to show off a bit so against someone who can shut him down quickly enough that ends up being his downfall.
Can she keep up the power null after he dies? All Fiction has a tendency to activate to erase death after the person in question has died, so if her power null stops at that moment he can still revive. If she can't then there's actually a decent chance for Misogi to win here.
As for Bookmaker, here's a quick rundown. Kumagawa uses a minus head screw that extends to pierce his target, usually as a thrown weapon though melee is also an option, and it takes effect at that point. Those affected by Bookmaker have their skills and abilities sealed. Anything Psylocke can do that Kumagawa can't, she can no longer do. It's a skill that brings the target down to the user's level. It's also impossible to gain anything from Bookmaker, so those weaker than him will not get stronger, and those who lack abilities will not gain any. It's also possible to strengthen the seal with multiple screws, though he's only done this once or twice and would never lead with it while in character.
As for how the battle goes, that depends entirely on Psylocke's first move in character. I won't be actively debating here but I'll give my 2 cents before leaving. Also, is the speed difference something I should be taking into account as well? If so that changes a bit.
Edit: Probably gonna be off the wiki for a while so I'll try to leave some useful information behind before that. Here's my take on the fight. Psylocke likely starts with either shutting down his mind to incap, or she power nulls and kills him while he can't fight back. If her opening move is an incap via mind manipulation and she's fine leaving him like that, she wins. Kumagawa won't fight seriously from the start so something that can shut him down instantly is a sure-win.
If she starts with power null, and it works even after physical death, then this is also a sure-win. Without BM and AF Kumagawa is much less dangerous, especially against someone who can stop him so easily, and he won't be able to revive or heal if her power null stays in effect. If she starts with power null and it stops working on him at death, then it's much more complicated.
After that first death, Kumagawa would realise that she is capable of turning off his minuses, so he'd instantly get serious. The end result would be instant use of AF to use his pseudo timestop/teleportation, to impale her with a Bookmaker screw. Should she keep trying to fight he'd keep hitting her with BM until she had difficulty even moving, then he'd either leave her in that state or kill her with screws to be sure. Erasing her with AF would be an absolute last resort, and is something he's never used in-canon during any sort of fight. He'd likely only use it against someone who can also revive, and only if BM didn't work, so that's not likely going to be a factor here.
That's how I see the battle going. Either she mindhaxes and incaps to win, power nulls and kills to win, or she power nulls and accidentally makes him serious and likely loses. Anything else would make for a rather drawn out fight and seems to shift the odds in her favour. For example, assuming she tries to fight physically she'd notice the fact that no amount of damage seems to suffice in putting him down for good, and she mindhaxes to win.
Power null and incapping is also a viable option should Kumagawa revive once and not get serious quickly enough. Overall she seems more likely to win, since she has more opening moves that result in wins that she's potentially willing to use, whereas Kumagawa will only get serious and try to defeat her once he sees her as a threat. Keep in mind I'm making this judgement with no information as to how Psylocke acts in combat, so take it with a grain of salt.
