Diamond Perfume (ダイヤモンド・ パフューム) is an organization built to chase characters with high ranks during the Character Poll Arc. Its goal was to have the highest rank among all characters. Though the organization was eliminated during the Character Poll Arc, they reappeared as a background band for Terakado Tsuu during the HDZ48 Arc They are supposed to spoof the real Japanese pop girl group Perfume (パフューム).
The Diamond Perfume was built for the mere purpose of eliminating characters that have a higher rank than their own members. They've picked the name Diamond Perfume to raise their popularity among their fans, because it sounded cute in their opinion. Nevertheless, they had no good intentions to begin with.
(Quote from Shimura Shinpachi about the Diamond Perfume) "They're nowhere as cute as perfume!...They're... They're... They're... 'vacuum'! A terrifying vampire unit which absorbs everything to become their own flesh!"
The members who voluntarily joined are all female, while every character who was "absorbed" and therefore forced to join were male.
The Diamond Perfume and its members are no longer active, though they've temporary become Otsuu's background band, though even then their only goal was to raise their own popularity to stand in the spotlight. As it was revealed in chapter 448, each member of the band has a major flaw that makes them less popular among the fans.
Shimura Tae is violent and treats fans badly and without respect
Diamond Perfume was built during the Character Poll Arc, when Shimura Tae, Sarutobi Ayame and Yagyuu Kyuubei complained about their comparatively low rank. When Kyuubei suggested to eliminate every character above them until all of them have reached at least the 10th place, the three girls teamed up. Their first target was Tsukuyo. Though before going after Tsukuyo, Tae departed herself from the group for a short while to eliminate Sorachi Hideaki. After Tae got rid of him, the three girls ganged up on Tsukuyo. Instead of just getting rid of her, though, Tae decided to make her join their group. Thus the four girls built the Diamond Perfume with Tae in the lead and had a new goal; Defeating and absorbing every character above them until they rank first. Their next target was Kagura, though they didn't intend to eliminate Kagura, but to make her join them as well. After Tae defeated the Shinsengumi's leader Kondo Isao, Kagura instantly abandoned the Yorozuya and joined the Diamond Perfume. The five girls then finally attacked the Yorozuya, the Shinsengumi and Katsura Kotarou. Tae took on Hijikata Toushirou, Kagura took on Okita Sougo, Kyuubei took on Katsura Kotarou while Tsukuyo and Sa-chan took on Sakata Gintoki and Shimura Shinpachi. Tae managed to defeat and absorb Kondo and Hijikata while Kyuubei managed to aborb Katsura. However, Kondo used the chance to drag the Diamond Perfume's rank down to a ridiculously low level. While Kagura tried to stop him and Sougo tried to support, the Diamond Perfume, the Shinsengumi and Katsura were attacked and defeated by Elizabeth and Sadaharu, which brought an end to the Diamond Perfume.