Mahou no Tenshi Creamy Mami: Fukigen na Ohimesama

The manga centers on Megumi Ayase, an idol singer at Mami's talent agency Parthenon Productions. Megumi is the top star of Parthenon Productions, and she is rude to Mami after she joins the agency. Megumi is jealous of Mami and sees herself as Mami's rival. The story follows Megumi's idol life as she tries to be a good senior at work to Mami.

(Source: ANN)