I don't get it...

The characters featured in the story, and then the characters released in the gacha. Isn't the bias too extreme? And it's characters like the Haitani brothers, Izana, and Taiju, more than the Toman members. Personally, I like Taiju, so it's tough when his gacha comes around frequently. He barely appears in the main story anyway, yet he's popular? That's also a mystery. Especially the Haitani brothers. But is Taiju actually popular? Or is it just easier to create events around siblings or characters like Inupi & Koko, or Mitsuya? I get that they have to make money from the gacha, so releasing popular characters is unavoidable, but isn't it too obvious?