Gen Shiomi, the 56-year-old boss of the Hitotsubashi mob syndicate, must go into hiding to protect his life from potential assassins. He opts to get plastic surgery, only to end up looking like a teenage girl, but he resolves to stay like this until his life is no longer in danger. However, he finds it hard to not be suspicious, but he is saved from being the target of police by a teenage boy named Tatsuya Umemiya. After helping Tatsuya out of some troubles of his own, Gen is forced to enroll into junior high school as "Shiomi Iwao", only to discover that one of his new classmates is Tatsuya.
Shitei Bouryoku Shoujo Shiomi-chan provides examples of:
- And the Adventure Continues: At the end of the series, with all his foes wiped out Gen goes under the knife to get his old body back. Unfortunately, when he wakes up he learns that his gang is now in a war with the Russian Mob, meaning that he still needs to stay in the body of a girl, with only thing the surgeon changed was to give him a boob job.
- Artistic License Biology: no way a plastic surgery would be able to change the look of a big man in a little girl, but this is precisely the point. This can be also seen as a parody of some episodes of Black Jack, where borderline/impossible surgeries are done.
- Be Careful What You Wish For: From Gen Shiomi to Shiomi Iwao.
- Belligerent Sexual Tension: Akane and Tatsuya. Akane has also a more sweet and feminine childhood friend who supports her. As Asako and Mayuko in Ushio and Tora. However, Tatsuya is no Ushio.
- Berserk Button: Tatsuya's reason for giving his money.
- Cliffhanger: with the hitmen.
- Love at First Sight: Tatsuya to Shiomi.
- Luke, I Am Your Father: definitely avoided in Chp.8. Gen, after he found to have a son: "There's no way I can do that". He is mentally trying to represent the scene, where he is still the schoolgirl with her usual angry look, doing the revelation to a very shocked Ichiro.
- Magic Plastic Surgery: Gen gets turned from an old man to a teenaged girl through a miraculous procedure. The surgeon in question chose this procedure partly because he modeled Shiomi's new body after an idol he's a fan of but also to ensure that he isn't simply killed off afterwards since he's the only one capable of reversing the procedure.
- Nightmare Fuel Station Attendant: the hitmen appear to be this trope.
- One is a bandaged blind man, with a sadistic streak, able to pursue his victims through scent and using butcher's hooks as weapons; then he is fond of speaking about the fear. Another, Kagachi, resembles a sort of snake woman (she is not). They obey to a Perpetual Smiler old man.
- It is possible that Kagachi consider the girl Shiomi Iwao in this way.
- Older Than They Look: Shiomi is 56-year-old made to look like a female middle schooler.
- Slasher Smile: Girl Shiomi does it often, in some cases masking it immediately putting a cute face.
- Shout-Out: The surgeon, the so-called "hands of God", is Black Jack by Osamu Tezuka. Not only the guy has his characteristic scarred dark appearance, he is also directly named as Kuro Hazama (at least in a translation). By the other side, some traits of his personality appear slightly different: after his work, he displays merrily some quirks of Takamizawa, the otaku of Midori Days.
- Took a Level in Badass: Shiomi can still fight after the surgery.
- We Meet Again: At the end of chapter 1.