ну, дорамщики все про это знают, но примечание все равно напишу ))
If you say 'manager' in Japan, it often indicates a 'towel boy' (aka waterboy) rather than an 'office manager'. Towel boys are the kids who hang out at the sidelines with bottles of water and hand towels to the athletes at sports games. So if you say 'joshi-mane/joshi-manager', it is generally referring to a female manager who takes care of sports players like towel boys do.
They also take care of equipment, sports team records, and more. Now, you can imagine that a lot of boys develop crushes on their joshi-mane, possibly because they are so helpful and supportive of all the players on the team during the school year.
www.tofugu.com/japan/joshi-mane/