SpoilerMost of her secrets - and personal problems - seem to be related to her prior relationship with Kaori Sakuragi, her now-deceased Etoile partner.
She is very skilled on the piano and likes to play it constantly. Much of the time, she doesn't enjoy the dull work of the Etoile, so she often finds ways to skip on her duties, much to the annoyance of Miyuki Rokujō. However, Nagisa manages to persuade Shizuma to resume performing her duties.
Voiced by: Nabatame Hitomi