|“||"If you can't solve this in one word, then use all the words you need. If you can't trust words to get the job done, then you can pair them up with actions. You can use any words and any actions that you like. Let each of them be a dot to connect until you manage to form your answer.||”|
—Shizuka Hiratsuka, My Teen Romantic Comedy SNAFU, TOO!
Shizuka is a tall woman with long black hair that falls over her shoulders and reaches her shins. She has unkempt bangs that cover her purple eyes. She is usually seen wearing a lab coat over her work uniform: a black vest with a dress shirt underneath, black pants, and a tie that she wears loosely.
Shizuka is an incredibly kind, friendly and responsible teacher who is open minded and believes in the future of her students. Pointed out by Yukino Yukinoshita, Shizuka wishes and works hard for the welfare of all her students. She cares about all the students which is perhaps best demonstrated when she becomes concerned about her student Saki Kawasaki regarding her late night job.
Despite her age, Shizuka enjoys reading shōnen manga to the extent that she often quotes or copies scenes from them; for example, she proposes a battle royale contest between Yukino and Hachiman Hikigaya. She also enjoys having fun with her students and observing their interactions, further demonstrating her youthful outlook.
On her days off, she drinks until morning and sleeps till noon. She usually gets assigned in charge of various school activities like cultural festival, athletic festival, the article of Love Marriage, Chiba Wedding, and Christmas collaboration event, etc. was pushed onto her by the top management. Shizuka believes her "young" age is the main reason why she keeps receiving those assignments.
Although she is young at heart, Hiratsuka is very aware and sensitive about her age and single status. She is quite worried her prospects of getting married; when her age and marital status are brought up, she becomes visibly agitated, either becoming incredibly violent as she does with Hachiman, or sad to the point of crying in front of her students.
She also shows her crafty side by tricking Hachiman into going to the Chiba village camp. She often shows her motherly, or care taking side.
Shizuka he is quite wise and hands out advice when needed. She is always ready to give advice and counseling to her students. She sometimes forces the students to take part in activities for their well-being. An example of this is forcing Hachiman to participate in the Service Club, Chiba Village summer camp, and as a Cultural committee representative.
In the light novel she is said to be excellent in martial arts and is hinted at in the anime by her displays of force towards Hachiman. Her skull clutch is described as an iron hold by Hachiman.
In accordance to her profession, she is also an excellent teacher and advisor. She can also play the bass as shown in episode 12. It was mentioned that Haruno dragged her to a concert in the past.
- "Don't think you can graduate in three years!"
- "Didn't anyone ever teach you not to bring up a woman's age?"
- "Helping someone out is not a justifiable reason for you to get hurt"
- "That holds true even if you`re used to pain, There are people who`d be hurt by watching you get hurt"
- "If you stick to your way, you won't be able to help someone when you most want to"
- "If you can't solve this in one word, then use all the words you need. If you can't trust words to get the job done, then you can pair them up with actions. You can use any words and any actions that you like. Let each of them be a dot to connect until you managed to form your answer.
- (To Hachiman) "Empathy, intimacy, curiousity, compassion, respect and envy. Harboring all of that and more towards just one girl. I'd say the word "love" definitely does not convey enough. That's why you're unable to part ways or be separated. Even if time passes with distance between you, you'll be drawn together. That maybe something you can call genuine." 
- The name Shizuka (静) means "quiet".
- Shizuka's surname Hiratsuka means "flat" (平) (hira) and "mound" (塚) (tsuka).
- Shizuka loves ramen.
- Shizuka was the Point of character for Track 2 of drama bonus C.D titled Tatoeba Konna Birthday Song (たとえばこんなバースデーソング, "Birthday Song for you") of Volume 3.
- Shizuka's hobbies are reading manga and Harlequin Books, as well as motorbike riding and watching anime.
- Shizuka's spends her days off mostly drinking and sleeping.
- Shizuka is a heavy smoker and is often seen smoking Seven Stars cigarettes.
- It was shown on the opening and on Episode 8 of Season 2 that Shizuka owns a Red 2005 Aston Martin V8 Vantage. When Hachiman Hikigaya asks about her former car, she said that she just rented it (The rented car that Shizuka refers to is a red van that was shown during their trip to Chiba summer camp in Season 1 Episode 7).