This is a good model, not only that it's finally a good sculpt for The Ito Clan, but her abilities are also good.
3 ki statistic is great, a good amount of useful traits and three good ki feats.
First the traits. Blood of Orochi (1), bravery, Light footed and steady are all things the other naga models have. Immunity (poison) is a nice and a logical addition, fear (5) is nice to give her some more survivabilty and more use in combat. The poison (2/1), while a strong poison trait, I don't think you'll use this very often because of her low melee skill.
Now her feats are good, we have the standard token feat every faction will have. The tokens have a some very good effects. Lightening reflexes is amazing, auto disengage and elusive is great to save an important model, armour (2) is never bad and finally sixth sense another good trait the tokens give. No bad traits in the list and useful in every game.
Her other two feats obey and paralyze is where we see a bit of a gorgon influence. Obey gives a target model a control marker when succesful, great and can wreck an opponents plan. Paralyze makes a target model held and slow a good combination of effects.
The three glaring cons are her rice cost, melee dice and ki max. With a rice cost of 12 you need to be careful of what you put in your warband with her as Mizuki will take a big chunk of your warband. Her melee dicepool is low, but this is acceptable considering this is a shugenja. Lastly her ki pool max is a bit dissapointing, I would have expected her to have a max of 10. It does help that you'll be using her feats often enough that if you fill you're ki pool you're doing something wrong.
She's very good at buffing any list she's in, her tokens boost any model that get them and her ki feats are very useful. Pairing Mizuki with a very good fighter like Masunagi could be very useful. Giving Masunagi lightening reflexes or sixth sense when surprised.