That's awesome, thanks. I think that's more than enough to start from. Here are my thoughts about it.
your avatar fuels my vigor for clarity.
Hayate: Wouldn't he be S rather than N? His communication skills are very poor, since almost every misunderstanding in the series seems to come out of his mouth.
How is this related to N/S?
He's very skillful with all the daily tasks and that kind of stuff too, what could be seen as a reinforcement for his ISFJ-ness.
ISFJ doesn't mean daily tasks and stuff. There is a connection but very small. Added to that, he 'needed' to be able to these things.
I'm not so sure why I think he's N. Probably something about "Santa Claus" and his really emphasized worldview: "Work is for people with poor parents and those who work will ultimately be brought glory." or something.
Nagi: ISFJs are too organized for her to be one, I think she'd be something like INTP. Well, since she's a child her type could be dubious, but like I said, they're all very caricatural. From this point of view she's definetely IxTP (as an unhealthy ISTP), but I think INTP is more passable.
Interesting. I find her too emotional to be Ti dominant. Her F seems to be extraverted and she has a pretty traditional worldview, so ISFJ I thought.
Organization has little to do with ISFJ.
Maria: At first I thought she really was INFJ, but I'm not so sure anymore. I think ISFJ would suit her somehow. To be honest, ISFJ works for her for the exact same reason that it doesn't quite suits Nagi.
The only thing that makes me think of Maria as N is her 'subtle' understanding of the situation. She doesn't do much but she has a clear view of the underlying emotions involved.(mainly between Hayate, Nagi and the rest of main cast.)
Hinagiku: I fail to see her as introverted, so it would be ENFJ or ENTJ for me.
Why? I could see Introvert with Auxiliary Fe.
When she deals with people, she takes high consideration about the feelings involved but she doesn't come off as domineering as Dom Fe. Like Maria, there is more subtlety to her.
I'm personally more fond of the idea of her being ENTJ, it has something like a tsundere air to it. With all the stubbornness included.
Speaking of the archetype "tsundere", there's usually a pattern.
Tsundere: Expresses "T" behaviors (often J)
Take, "Hitagi Senjougahara". INFJ or INTP.
1. She talks a lot and is often 'bossy' but her 'aura' is still introverted.
2. How can "IxFJ" characters be "tsundere"? It's because of the functions coming of as PiTi and the allowable repression of Fe. Added to that, "J" permits 'pushiness'. ExFJ's, on the other hand, aren't tsunderes.
Sakuya: Dunno, nothing against her being ESTP.
I saw healthy Ti, as compared to Nagi's Ti.
Wataru: I think he'd be ISTJ. From the point of view of handling the mistakes he makes himself, Wataru is way too honest and composed to be an INTJ.
How is being honest and composed unrelated to being INTJ as compared to ISTJ?
I don't know about his N/S much. He remembers a lot of movies?Nah...
Athena: I'm thinking about xNTJ. And the way she dealt with her relationship with Hayate makes me sway for I.
I've never seen/heard this character. I didn't really finish second season.
Too sleepy to think right now, but I'm bracing for Tama's type.
Tama? The carefree lion that talks so infrequently?
ENFP?