Glass Hime to Kagami no Juusha

Royal Cendrillon Academy.

To fulfill a promise, the protagonist Takita Shunsuke enrolled in the attendant department.
There, they are tasked to serve a student from the royal department as part of their extracurricular activities, attending to all kinds of princesses.

"Or, that was how it was supposed to be---"

Committing a blunder on the day of the entrance ceremony, Shunsuke now faces the threat of repeating a year halfway into the school year.
The girl he exchanged a childhood promise with, Bernadette Henrietta Eiselston
The son of a royal prince with a secret, Anri Francis La Bernard
The young lady of a large corporation with an eccentric tongue, Sasara Orihime
The mild-mannered classmate, Shirokama Naomi

Obtaining the aid of various people, Shunsuke traces the path toward becoming a full-fledged attendant.

All for the sake of the "promise" he once made.

[From official summary]