The main teacher of Asahi and co's class, she actually knows about all their secrets, but is more busy dealing with her devilish ancestor.

Badass Teacher: She is pretty much the only force capable of making Akane pay when her pranks go a little too far.
Christmas Cake: Reminding her that she is single isn't the best of ideas. She couldn’t get a boyfriend in high school and has gone to one hundred marriage interviews in the present. When she thinks Shirou is flirting with her, she gets all blushy before he flat out says he simply admires her and that she’s too old for him. Turns out, she’s set on a prince riding in a white horse. Literally.
Cool Car: She buys a new one at some point and takes the party to a trip with it. Then she lets Akane drive it when she is asleep after drinking too much.
Akari: Hahaha... why would you apologize? I'm just asking a single question. Where is my brand new car? [cue the ruined car in the background]
Hard-Drinking Party Girl: She has an immoderate taste for beer, which is the cause of the above incident.
Informed Deformity: Think Akari is pretty? Well, you’re wrong. She is so lacking in sex appeal that it rubs off on Shiho. Though it's less because of her looks than an abstract "aura" that she emits (her trademark jersey and rather boorish manners don't help).
Japanese Delinquents: Used to be one, and would rather not let anyone know about it. There are a hundred stories of her legendary exploits
Man Child: Despite being a fully grown adult, she's waiting to be swept off of her feet by an honest to god prince on a white horse.
Only Sane Man: Boy does she try her hardest. She has some sympathy towards Asahi because she knows exactly what he's going through. However...
Not So Above It All: Once we find out about the chain of humiliating failures that is her love life, warped views on finding a soulmate, and idea of "sexy," it becomes abundantly clear that she's no better than the craziest of them.
Red Baron: "Akari of the Hundred Visits." This mysterious and fearsome nickname refers to…
Running Gag: Her overwhelming "singleness." It's enough to make Shiho forget how to act sexy. It's so impenetrable that not even the combined power of several gods of fortune can grant her wish of having a boyfriend.
Sensei-chan: She averts it for the most part, staying relatively formal with her students (relatively), hence why she is in shock when
Akane: Welcome to the world of idiots.
Slasher Smile: Much like Akane, she has a tendency to break out into comedically creepy smiles when someone stirs up trouble —especially Akane herself.
Sophisticated as Hell: She can speak politely and respectfully to Akane one second and call her a stupid old hag the next.

(Source: TV Tropes)