Bertie is second youngest of the Ayakashi Sisters. Her powers are based on water. She joined Sora's team due to her crush on Sora. She vows to win his heart fair and square and attempts to wait for him until Sora's older.
In Sailor Moon
Berthier is the first sister sent by Rubeus to take over Crystal Point in Tokyo. She has two solo missions and the droids she used were Atsugessho and Nipasu.
After Kōan left the Ayakashi family, Rubeus sent Berthier to take over a crystal point in a chess building. Ami Mizuno encountered Berthier and transformed into Sailor Mercury to fight her, revealing her true identity to her. Berthier retreated from the battle and entered the chess tournament where she faced Ami in the finals. Although Ami won, Berthier trapped the other Sailor Senshi in a ball of ice and started another game of chess with Ami, except this one was with her own rules - whenever Ami lost a piece, a part of her body would freeze. The spell was shattered by Tuxedo Mask, who freed all the Sailor Senshi and Berthier's plan was foiled. Calaveras and Petz had appeared to reclaim some of the credit when Berthier's had the advantage but explained that Rubeus was going to kick her out for her failure and abandoned her. Berthier, alone and out numbered, broke down and attempted to freeze herself to death. Kōan convinced her to stop and change her evil ways so Sailor Moon used Moon Crystal Power on her.
Berthier was later captured along with Kōan by Calaveras and Petz, in an attempt to turn them evil again but in the battle that followed, Rubeus ditched Calaveras and Petz and they were also healed of their evil. Berthier is the second of the Ayakashi Sisters to turn good.
Story of Joining Sora's Team
When Sora and Kairi started their first date on Sailor Moons world (on her Earth) they had a picnic and had a great time when it started. But when Heartless were attacking the citizens of the city, their date was cut short as Sora had to fight off the Heartless. And when the Castlevenoms attacked Bertie, she fell in love with Sora when he defeated the Castlevenoms and saved her. But when she hugged Sora and kissed his cheek, Kairi became angry and Sora tried to make up for his mistake. But when he tried to, Bertie followed them to the ship and when Sora and Kairi made up, Bertie became jealous and jumped out and grabbed Sora and hugged him tight and kisses both his cheeks. Then Kairi challenged Bertie to battle, but when the two started to fight, Bertie's sisters came on the ship to take Bertie back with her, but when Bertie tells her sisters that she's in love, they all decided to let her as long as her sister join the team. But Kairi tried to tell the sisters about how Bertie wasn't even a member, the Ayakashi Sisters group hugged Sora and begged, and as Sora was struggling he let the sisters join and it made Kairi upset. As some of the members came back on the ship, the Sailor Scouts came with Riku, Goofy, Lock, Shock, and Barrel, while An & Ail came with Donald Duck, and Roxas.