She's the student council president at Shinsen Middle School and loves to take care of others. She's a very skilled karateka and enjoys to eat fruits parfaits. Her family owns a fruits and cafe parlor called "Fruit Parlor KASAI."
Amane was brainwashed by the Bundle Gang to do their evil deeds as Gentle. Throughout the first few episodes, Gentle steals the Recipippis and summons Ubauzos when the Cures catch her. But from episode 8 onwards, Gentle starts experiencing headaches, with Amane continuously appearing within her to tell Gentle to stop hurting the Recipippis.
Later, the girls trick Gentlu into targeting a hamburger steak restaurant that hadn't opened yet, not knowing it opens early, to try and talk some sense into her, but she refuses to listen. While she rebukes Precious' attempts to befriend her, the control starts to waver again after Precious shows her a drawing of a Recipippi Amane drew. She tells the Cures to break the spell over her, but Godatz intervenes and sends her dark heart to the Ubauzo to strengthen it even more. However, the Cures use MIX Heart Attack to purify it and destroy the heart, freeing Gentle from Godatz's control and turning her back into Amane. She later returns to her home and has to temporarily leave school to recover both physically and mentally. After some episodes she matures the desire to become a Precure. She then transforms into Cure Finale.