King = like Nile said, Hana is really nice already and needs very few tweaks.
If the shyness issue can be played down and her outgoing personality played up I think you'll find that helpful as well as it helping everyone else. She can still be of the shy, sweet, cute, innocent type if the moe character appeals to you to RP but that need not make her quiet and introverted. She can be outgoing but still of that moe-like disposition. We have a couple of girls like that already in the game and they are both extremely popular characters, so I see no big deal with a third girl like that.
Hana can have her fetish as nudity, no problem, but as Nile said, there will be very little opportunity to exploit it in the normal school day. That being said there might be opportunity to do another gym or swim class and there's locker room nudity plus our last swim class was conducted fully nude for everyone
We have a sports festival coming up on the following day; there might just be some opportunity for nudity there, not sure yet.
Hana as Nile and you both suggested, can enjoy her naturist tendencies around the dorms and outside classes away from the main campus buildings. I have a character called Momo who likes to sunbath nude and sometimes doesn't bother covering up around the dorm but I haven't actually had ANY opportunity to play that facet of her personality in the entire 2 years the game has been running so please be warned!
What we could do is play it so that the Social Club seniors find out about Hana's fetish and exploit it that way. Perhaps rather than have her lacking pubic hair to begin with, the SC can have her waxed. There's even a victim girl of the SC whose job it is to regularly shave the SC girls. That might be more fun for you and Hana? Likewise she can have naturally light hair but as part of her SC makeover she could have it changed to lilac. Its not dyed BTW but actually recoloured at the DNA level using drugs invented by Morimoto Pharmaceuticals Division, so no matter how long it grows and is cut, its always lilac. If she had pubes they would be lilac too so there's a possibility of a small cute patch of that colour being left high on her mound for fun but her lower area left smooth maybe.
Large breasts are a bonus. We have several characters who like them!
I agree with Nile that it works far better if the father alone was caught in some wrong-doing with a fellow (very senior?) employee and no Morimoto family member was directly involved. It helps make the blackmail more solid and less risky for the family.
Phoenix = I like everything about Tetsu, he seems almost perfect for the game. I'd be wary of just 2 issues. Firstly his sexuality seems extremely highly developed for a 17 year old with a long range of established kinks. Obviously these are your ons which is fine but maybe you can downplay them somewhat for Tetsu himself so that his school life becomes something of a journey of discovery for him as well. He could even be a virgin which could give us some amusing material to work into an early scene. If you clarify that he himself is just recognising a submissive side... maybe he's become aware that he likes looking at porn websites of a BDSM nature but it is only in the last year or so has he discovered that he identifies with the submissive roles depicted on his computer screen more than the dominant roles? Exploring the kinks he likes and drawing them out of him can be a part of his sexual training.
Please also be aware that with so many student characters, not all of them can be given opportunities for training scenes etc so he needs to be a character who can fit into general school activity scenes as well as the more overtly sexual ones.
The second part of the character sheet that concerns me is his fathers business. I see no reason why the powerful Morimoto Corp would give financial aid to a lowly grocer, especially considering that if the grocery business fails its no loss (or even interest) to the Morimotos. Now if the father owned a business which the Morimotos did rely on and it went under, then we have a good reason for them to step in with financial aid. If we change his family business to one that, say, supplies small electronics components and has done for many years (at a rate the Morimotos cannot easily get elsewhere), then when it goes down the tubes they step in, give the father a huge loan and take Tetsu as collateral. Lets also add the additional burden that the business is very old and has been run by the family for generations (prior to it focussing on electronics it dealt in other kinds of shipping and trading - it could even be a mercantile concern going back to the colonial days of the pre-Meiji era) so that should it fail, Tetsu's father would lose all honour as being the Moriyama whose inept business skills was the weak link in a long chain of otherwise proud and capable Moriyama's. That should place enough of a burden on the poor man that he agrees to the deal, gives up his son and keeps his mouth shut so his wider family is none the wiser.
Other than that Tetsu sounds quite a good fit for the game. If he is switchy he can be let loose on the girls in a dominant role from time to time but as a more submissive boy the Social Club could identify him as a possible candidate to be turned into a male whore who would be given to the family's female (domme) clients to work him over for their entertainment. His training would therefore focus on instilling in him obedience and enjoyment of various abuses, bondage, CBT, etc. If his kinks don't specifically mention these at the outset but he grows to love them I think that works better.
Your thoughts on those suggestions?
Also have you any other pictures of the character - the same goes for you King - we can use additional images in the post header avatars and Tetsu's face in that pic is a little obscured. A clearer one would be very useful.