Tatsumi Koutarou

 is the producer of the Saga-based idol group. He appears only in the This Is Our Idol SAGA! event.

This Is Our Idol SAGA!
While on their way to their hotel, Aya accidentally opens her travelling bag at the airport and Kotarou, who happens to be near her, offers to help her. Aya thanks him for his help and after leaving, Kotarou realizes she and the other four are members of Pastel*Palettes. Chisato notes that his gaze was still lingering on them, but decides to drop the subject at hand. Pastel*Palettes meet him again at the hotel they are staying at, after putting on the "relaxing body cream" given to them by the agency staff and having to find a place to hide in. He is mad at Pastel*Palettes for taking Franchouchou's spot in the, calls them thieves, and tells them he doesn't believe such city idols could handle that gig.

As they meet again multiple times, Koutarou constantly belittles and yells at them, but at the same time gives them advice in his own way, which leads to Pastel*Palettes realizing what they've been doing wrong.

Trivia

 * He is the only voiced male character in Girls Band Party!