ask the band
They were first hired to be a great band. At the beginning of the series, ASK was already becoming a popular band and Tohma Seguchi was their producer.
However, when Shuichi Shindou's band "Bad Luck" started to become popular after being the opening act to Ask and being on a game show, Ask was starting to fall behind and Taki Aizawa, the lead singer, started to grow resentful. He made it worse for his band when he had a group of men beat Shuichi and took a picture of it to blackmail Shuichi to quit the music industry or he will reveal his and Eiri Yuki's relationship and have Yuki's reputation be tarnished, and the picture would be used to destroy Shuichi and his band's career as he made it look like Shuichi was prostituting himself to his attackers and would make NG records look bad. His band mates were shocked and horrified by what Taki did to Shuichi.
However, when Eiri Yuki found out what Taki did to Shuichi, he went after the band and beat up his guitarist, while in the manga he beaten up all three of the members of ASK and not just Ma-kun, and forced him to give him the picture of Shuichi being beaten and touched by the thugs. Soon Taki makes Yuki a personal target as he wanted revenge against him and knew he was Shuichi's weakness as he loved the man, then Taki finds out that Yuki killed people when he looked into his eyes and saw the eyes of a killer and declared he would find out his murderous past and use it to end Yuki so he can destroy Shuichi.
Aizawa's plan failed when Tohma found out what he did to Shuichi from his jealousy and what he tried to do to Yuki, calling him a fool and if he stayed quiet he and his band would have a decent future. Tohma goes on to say that now he threatened his brother in law, there were going to be consequences, he pushes Taki Aizawa in front of a car, while he was not hit he was terrified and Tohma bid him farewell. In the manga before Taki was confronted by Tohma, he finds Ma and Ken and calls them traitors for telling Shuichi his plans, with Ma and Ken telling him he's gone to far with his jealousy and revenge and that it's all over for him, ending their friendship as well as kicking him out of ASK as they knew Tohma would terminate his contract and possibly have Taki arrested for what he did to Shuichi. And instead of the car stopping before it hit Taki, in the manga he was hit and killed instead of simply being fired from NG like in the anime.
Because of Taki's actions against Shuichi, putting his band mates in danger and attacking his boss's brother in law, ASK disbanded, Taki's band mates turned on him and his career was destroyed.