Tamaki is a friend of Keiko and Rinko Nikaido. In the anime, she is shown as a regular high-school student and long-time friend of the three, but in the manga she starts as a 'ganguro' bully that extorts money from Keiko on a regular basis, before later changing her ways and bettering herself. 
Tamaki Maekawa (前川たまき, Maekawa Tamaki) is another one of Rinko Nikaido's best friends. In the manga, she is a ganguro kogal that bullied Keiko in school, but later had a change of heart after The Rigany kidnapped Rinko. In the anime, she appears along with Rinko and Keiko during the Tel-Tel Boy fight. Along with her two friends, Tamaki cheers on Team AHO for the majority of the anime and manga. She is the first hostage up for grabs in the Poison Six Pack saga, and is saved by Terry the Kid and Jade, with Kid catching her.
In the most recent manga arc, she stays behind in the present timeline with Keiko. It's unknown if these two know if Rinko sneaked on board the time ship. We mostly see Tamaki alongside Keiko and Rinko in the series, where she provides support as a wrestling fan to various teams. She has no love-interests, nor is she see seen to have formed close relationships with anyone outside of that particular trio of characters.
Tamaki often wears a purple turtleneck shirt, which is sleeveless, when she is dressed in casual-wear.
Tamaki is introduced as a student of Shirobara Private High School, a private all-girls school, and is a part of Class B. We see she is a 'ganguro' fashionista and is demanding money from Keiko, who can only provide 30,000 yen. Tamaki states that if Keiko has no money, she can turn to prostitution, and physically attacks Keiko. It is at this point Rinko intervenes and Tamaki flees, seemingly not wanting to enter an altercation with Rinko.