>>282989539
Saying that, Chiyo was definitely behind Arisu's last minute transfer to Gloriana. Moving schools is a complicated procedure that has to deal with bureaucracy, and Arisu is a very special case where a child prodigy enrolled into university wants to degrade to Highschool. Also, Arisu was able to bring her tank too, and that needs to be approved by the federation. This simply can't be done in a short time, but to consider that Arisu told Miho she didn't decide which school to join by df2(after the 1st round), but already joined Gloriana in df4(between round 2~3), the procedure was done very fast.
Also as >>282987080 said, chiyo can be the key person to bring upgrades to Gloriana disguised as presents, but in reality being part of her plan to help arisu. Gloriana cant use new tanks because of their Alumni, and it's possible that the inclusion of Arisu's Centurion may have unpleased them. In this case, if Gloriana's Alumni council acts uncomfortably with Arisu, Chiyo is the one to intervene and stop anything that might impede her daughter's senshado career. Besides, she may even slowly plan to take control on Gloriana for Arisu to thrive on highschool.
She'll still maintain a friendly face, but behind that she would already have planned her own scheme to help Arisu's highschool life by giving her the spotlight and letting her smash oarai in her highschool debut match, while trying to gain control on Gloriana again to help arisu, and use the school to foster new shimada athletes before university level senshado.