Pearl Pink by by Tanaka Meca (amazon)

Kanji’s father runs a successful talent agency called Dog Run. Their cash cow is the actress Shinju Momono who stars in the TV show Idol P.I. Momoko. Shinju has a daughter named Tamako. 10 years ago, Kanji promised Tamako that he’d marry her if she stopped being a cry baby. In the present day, Kanji is returning home after being sent on an errand to pick up some magazines of a questionable nature for his father. He sees some junior high kids picking on a younger kid and is about to step in when the kid shifts into ninja mode and beats the bullies up. The kid recognizes Kanji, calling him Kan-San. Tamako is 13 years old now, and she’s turned herself into a self-reliant tomboy because she expects that is the way she’ll win Kanji’s love. Kanji barely remembers Tamako or his promise, but he humors the “monkey girl”. Tamako moves in with Kanji and his father, because they can’t allow the press to find out that Shinju had a daughter when she was a teenager.
Tamako is dismayed to find out that Kanji’s “wifely” skills are better than her own, as he excels at making box lunches and serves as a fashion consultant to his father, who seems to enjoy dressing up in potential outfits for his female idol in order to get Kanji’s expert reaction.
Although there’s a 3 year difference in age between Kanji and Tamako, she’s drawn to look much younger than 13. This has the potential for ickiness, but it is mostly sidestepped by Kanji’s continued insistence that Tamako’s goal of becoming his wife is ridiculous because she doesn’t really know who he is or what love is.
The art is clean and attractive, easily rendering moments of emotion as well as Tamako’s monkey-like physicality. There are some cute side stories that detail the plot of the Idol P.I. TV series. While I have to say that if you only read one manga of the idol factory genre, Skip Beat is probably the best option, Pearl Pink does have plenty of cute moments.