Momo has brown eyes, and wears standard Shinigami robes, with her black hair pulled into a bun held in a tied cloth. When in her Shinigami robes, she wears the 5th Division's lieutenant armband. While in her pajamas, a plain kimono, her hair is tied in a loose ponytail. When she attended the Shinigami Academy, she wore the red student's robes assigned to the girls, and her hair was in pigtails tied at the base of her neck.
17 months after Aizen's defeat, Momo wears a new hairstyle; no longer tied up in the back, it hangs down in a bob, with a clip on the left side.
Momo's main pastimes are reading and drawing. Due to her talent in drawing, she has overseen work for book illustration in the Shin'ō Academy. Her love for books has developed since Aizen regularly gave her the books he had read. In his absence, she frequently visits the library. She attends the ikebana lessons held by Captain Retsu Unohana. She frequently visits her and Tōshirō's grandmother in Rukongai. Her favorite food is peach, and she does not like plums. She sometimes bakes cookies, and once made a batch in the shape of Aizen's glasses.
Momo is generally an upbeat, easy-going, and friendly girl. She has a strong friendship with Tōshirō Hitsugaya, whom she grew up with, repeatedly calling him "Shirō-chan", despite his higher rank and complaints about this. Though normally kind, her rare bouts of anger can appear rather menacing, such as her outrage at Captain Gin Ichimaru when she blamed him for killing Aizen. While serving as his lieutenant, Momo greatly respects and admires Aizen. She idolizes him to the point where a letter from Aizen leads her to attack Hitsugaya, her childhood friend, and even after being stabbed by Aizen, she, proclaiming Aizen was being manipulated, asks Hitsugaya to save him. When Aizen leads an attack on the fake Karakura Town, Momo helps to defend the town from Aizen and his forces, but she still notably refers to him as "Captain Aizen".