Shitt P! was one of the new transfer students from Shimon Middle High School that came to Namimori after an earthquake hit their area. She first appears in one of Tsuna and Gokudera classrooms, when one of the teachers at the school mispronounces her name. She quickly shocks everyone in the classroom due her strange behavior and appearance. Gokudera too is shocked like the rest of his classmates because of her appearance, and assumes she is not human, and that she is sending him signals. Gokudera starts to believe that she can only be an U.M.A., and starts to write memos about her. It is when Kyoya Hibari gets into a fight with one of the transfer students on the school rooftop, that her and the other transfer students' identities are revealed. Reborn says that the transfer students are part of the Simon Famiglia, and are Tsuna's guests who were invited to the Vongola Inheritance Ceremony.
Later on through the day, Gokudera finds out that Tsuna was attacked by a hitman hired from another family to stop the ceremony, and demands a meeting with the Simon Family. The Simon Famiglia members (except for Shitt P! who was meditating) and Vongola Guardians all meet at Nammy's restaurant, discussing how to protect Tsuna in each area of Namimori. Gokudera creates a plan which separates everyone into groups. Adelheid tells the others to inform Family members who are absent from the meeting about protecting the Tenth. The next day the Simon all agree to protect Tsuna, and that every day a new member will protect him.
A few days later, it was Shitt P!'s turn to protect Tsuna, Gokudera offers his help too. But when he got to Tsuna's house, it was later revealed that she had been standing still the whole day. Reborn even stated that when he did some doodling on her face, and forced bugs into her mouth, she still didn't move an inch. Reborn says that she's completely useless, since she won't communicate with them. When Gokudera tries to communicate with to her, P. just sticks out her tongue and leaves. Gokudera then chases after her and sees Adelheid walking out of factory warehouse. Gokudera becomes suspicious because she was alone, but she told him that she was just taking a walk. She then asked Gokudera if he was getting along with Shitt P!, but he responded by saying that he couldn't understand her. She later gave him hints on how to communicate with her by telling him that P. had been sending him signals from the beginning. Gokudera then remembers that Shitt P! likes to be called "Shitopi-chan", and called her so. To his surprise she responded to him. The next day, P. is seen at the Vongola Inheritance Ceremony with the rest of Simon Famiglia, who were all surprised to see Takeshi Yamamoto. She is later seen amongst the crowd during the ceremony waiting along with the rest of the Simon Famiglia, when Tsuna was to receive the Vongola Sin from the Vongola Nono.
After an explosion, the sin was broken open, supposedly by Enma Kozato. The Ninth revealed that the Sin in the ceremony was merely a fake. He proclaimed that the real one was in a safe that was impossible to penetrate. However, the safe was broken into, revealing Shitt P! and Enma with the rest of the Simon. Enma stated that they came to the ceremony to take back the "Sin" for the Simon Famiglia, and to get revenge on the Vongola. Tsuna asked Enma why they attacked Yamamoto. Enma responded that it was because he was a Vongola Guardian and it was a "rightful atonement." Enma then went on to explain that the Sin belonged to the Simon Famiglia and that it was the blood of their First Boss. Enma declared that he will inherit their family as the Tenth Boss and take revenge on the Vongola by gathering Mafia from all over the world and standing above them as their leader. The purpose of the war was to gain back the pride of the Simon. Shitt P! and the others then released their rings as Enma said that the reason that Vongola Primo got rid of the Simon was because they had a power that rivalled the Dying Will Flames of the Sky, which were the Dying Will Flames Of The Earth.
Enma then went on to defeat Tsuna and his Guardians. The Simon Famiglia then took their leave and take Chrome Dokuro with them back to their home. Shitt P! later reappears with the rest of the Simon at their home land, when Tsuna and the others come to get back Chrome. The Vindice too appear, and claim that if the two families are going to fight, they were obey the Vindice's law. Vindice explain the history between the First Simon Boss and Primo.
The Vindice take their leave, but before going Adelheid Suzuki ask how would they know who wins the battle. The Vindice Guardians reply back that if a guardian's pride is broken during his/her fight, then the other family wins, and the loser is hauled off to Vindice to be locked up for eternity. Simon Family tells Tsuna and the others, that since this is their home land, they won't engage in battle yet. They would have to follow one road that leads to them. The Simon then leaves. After Kouyou and Ryohei's battle, she too received the flashback memory of Giotto and Cozzato, and was shown to have gathered with all of the other Simon family for meeting. She is later seen in a town that is similar to appearance to the town where Giotto, G and Cozzato lived. She then meets Gokudera, and starts the battle. She states that Gokudera is weak, as his pride is based on Tsuna, instead of himself. Shitt P! used Tsuna's statistical information to discourage Gokudera, only for him to tell her that he already knew, but he doesn't care.
Stunned, she felt her other balloon explodes. She turned around to see Uri about to attack her. However, instead, Uri goes back to Gokudera. He then explained that he had placed catnip on her when she first attacked him so that Uri attacked her on its own. Being the loser, Shitt P! gets handcuffed by the Vindice. She receives the memories from third key. Afterwards, she claims that the war Simon and Giotto were talking about would lead to Giotto's eventual betrayal and saying that their claims were coming true. On why her pride was being she was that when she was younger, she was discriminated for being weird. After a while, she decided to tell herself that she was right in her own way and should care about others. Before she was taken away, she tells Gokudera that even though they battled one another, she wished to have met Gokudera earlier, calling him a "warm U.M.A". Instead of disagreeing, Gokudera seemed to accept it. Just as Vindice disappeared, an object is thrown towards the disappearing Shitt P!. However, it was too late by then, as she had been taken away by the Vindice.
At the end of Demon and Tsuna's battle, she and the guardians of both families are released from the Vindice Prison. Later, she is seen "stalking" Gokudera from a distance in her race car.
Later, when Adelheid stumbles upon Enma and Skull after them nearly getting killed by Team Mammon on the first day of the Representative Battle of the Rainbow, Adelheid thanks Skull for saving Enma and agrees on behalf of the other Simon Guardians to become part of his team in the Representative Battle. Thus, Shitt P! joins Team Skull.
On the second day, no one challenges Team Skull until just before the battle ends, whence a group of Vindice that eventually become known as Team Bermuda appear and defeat all of Team Skull in an instant, stealing their Rainbow Wristwatches to enter the battle as well. Team Skull is mortally wounded, but still alive at this point.