Shizuna Yoshida
Reiko would challenge even an asura in all his six-armed glory to an outright swordfight instead of mere kendo if her adrenaline was already flowing; Shizuna's aura of fear and intimidation means little to her. Shizuna's choice to not speak much in direct conversation will no doubt bug Reiko more and more over time, but eating some food together now and then should keep it from getting to her too much. Just so long as it's not Italian. If nothing else, Reiko would be glad to meet somebody else who can't stand Italian food. She'll also probably reject Shizuna's protection if it's outright stated she's trying to protect Reiko, and would instead start doing her best to be the one doing the protecting instead. She's the one with the shinai, after all, and she sure knows how to use it.
Total relationship analysis: Seems that Reiko's liking for this girl may very well become an on-and-off thing.
(I kept almost typing "Shizuna" as "Shinmyoumaru". You know you're addicted to Touhou when...)

Akane Kabetaki
If nothing else, being taller than Reiko will make her look up to Akane, even if it's just a little bit. Akane's motherly personality may also lead to interesting interactions between the two, with Akane worrying about Reiko and Reiko not seeing what the big deal is at all, then possibly later trying to protect her if the two wind up friendly with one another. As an only child, Reiko can and will fail to understand Akane's love for her sister, but she will respect Akane's choice to take up karate. The one and only time Reiko ever fought without a shinai was the time that made her decide to try kendo to begin with, and she would say there's a lot said about a person if they prefer their own body as a weapon over an "actual" weapon. She wouldn't dare spar with the girl though; an armed kendo club president versus any karate club member that isn't the president doesn't feel like a fair fight to her.
Total relationship analysis: Reiko will either just not care about Akane at all, or see a friend in a fellow warrior.

Audrey Ordeñez
Being from one of Osaka's biggest tourist spots, Reiko has seen her fair share of foreigners already and developed her idea of how to treat them from the city's vendors and merchants. Because of it, she'll end up being surprisingly polite with Audrey, at least at first. Audrey's somber and monotone demeanor will no doubt get to Reiko over time, and it will show somewhere down the line that it's bugging her. If things get real sour and Reiko's already in a bad mood, she may even try to fight the negativity out of Audrey despite her normal tendencies to only take fights she would consider a challenge. But despite all that, she won't let anyone give Audrey crap for the very things she dislikes thanks to her extremely anti-bullying views.
Total relationship analysis: No matter how many ways I look at it, it's Reiko's fault they won't get too friendly.

Aito Shiba
One boy with all these girls? Reiko may not be big on anime, but she's seen enough to know where this is going. And she absolutely refuses to accept being part of any harem. No doubt Reiko won't like his showing off, either, be it about his dogs or his fake glasses. Then there's the way he acts with others. While she may not notice his antisocial antics at first, Reiko will no doubt trying to straighten the boy out once she starts noticing them. She'd rather pair up with one of the girls than this guy once she paints a negative image of him in her mind, and if he tries to ditch her just to see tomorrow, she'll make sure to stay one step behind him to take him down with her for what she'd label as selfish cowardice.
Total relationship analysis: This ship's not setting sail anytime soon.

Shiori Mizuhana
...actually, Xalt summed this one up pretty well at the top of the previous page.

Reiko Nagatani
How is Reiko supposed to have a relationship with herself? Unless her very different attitudes with/without an adrenaline rush end up becoming split personalities. In which case, I'd ship the hell out of that.

Shinobu Resan
Reiko would leap at the chance to meet somebody else who practices kendo. She'd also offer Shinobu join the club, no doubt, but wouldn't accept any challenge Shinobu issued until she saw just what the girl was capable of. Even if she knows how naïve it is, she'll also appreciate Shinobu's view that everyone is a good person deep down, and would equally appreciate how well she treats others. If/When it begins to set in that they're not exactly in a safe place in this RP, Reiko would most likely train Shinobu to hone her kendo skills so that it wasn't just her own skills she'd feel safe with. A fellow kendo fan is the last thing Reiko's expecting, so the foot these two get off on could very well turn into something of a wildcard.
Total relationship analysis: Reiko/Reiko aside, I'd ship this most for Reiko Whether they get off on the right foot or not, Reiko will inevitably form a positive relationship here.

Shiori Mizuhana: Claims to know nearly everything about her. Oddly enough, Shizune considers the president of the P.O.I.R club to be a close ally as well as someone she can constantly rely on. While most would simply perceive this as simple admiration for Shiori's position and reputation, Shizune claims that their bond goes beyond that, despite the fact that they literally just met each other in the span of one day. The one Shizune will most likely partner with.

Kabetake Akane: Claims to know nearly everything about her. Despite the girl's motherly affections to the rest of the group, Shizune knows from experience of the hidden pain and turmoil Akane attempts to hide. Additionally, Shizune also believes that deep down she is the most fragile of them all mentally. Regardless, she holds Akane in high esteem for what she commits to the team. The one Shizune respects the most.

Audrey Ordoñez: Claims to know nearly everything about her. As another fellow transfer student, Shizune understands the harshness of leaving and losing certain people that are dear. Not much interaction is seen between the two on Shizune's part, but the red-eyed girl still treats her as a valued friend. The one Shizune can emphasize the most with.

Aito Shiba: Claims to know nearly everything about him. In doing so, Shizune can usually overlook Aito's behavior. Usually. Despite knowing that the asshole act is just that, an act, she still gets aggravated at his constant superiority complex and whining in critical situations. The one to cooperate the least with Shizune.

Reiko Nagatani: Claims to know nearly everything about her. Shizune often finds herself ressenting Reiko's loud nature as well as her willingness to fight. Furthermore, she can't help but feel annoyance at Reiko's stubborn nature of protecting everyone by herself, giving Shizune the impression of arrogance. However, Shizune marvels at both Reiko's incredible combat skills as well as her passionate vendetta against injustice. There's also the fact that they both dislike Italian food, but for obvious different reasons. The one that rivals Shizune.

Shinobu Resan: Claims to know nearly everything about her. Shizune, like most others, can't help but admire Shinobu's constant optimism, especially in these darkened times. Even so, she also feels that her philosophy on people is flawed and that her simplicity can attract much unneeded danger. The one Shizune will most likely protect.