Reiko first appears to warn Himoto Sora not to battle her owner, Vice-President of the Student Council, Sumita, and if she does, to lose. However, Sumita then appears and challenges Sora. While Sumita and Sora fight, Reiko and Oashi Tomoko are standing in the sidelines, confused as to what is happening because their masters had disappeared into the woods. When Tomoko questions her relationship with Sumita, Reiko replies that she is only using Sumita; unfortunately, Houjou, disguised as X, recorded her saying this on his cell phone. When Sumita purposely loses, Reiko almost immediately orders Sora to release her, which Sora complies to.
Later, she sneaks into the Student Council building. She recollects the best person to be with, who is Sumita, as he had never laid a finger on her, and actually protected her from Sora's spear.
Although Reiko managed to return to the Student Council, her possessor is switched to Togyu Shirou, who constantly abuses her. He also reveals to her that L commanded him not to release her, thereby crushing her dreams of escape.
She ends up in the infirmary, where Sora sees her again.
After Sora's glove got ripped, Hiyo and Togyu Shirou moved their sights onto Reiko. When Togyu was about to attack her, however, Sora intervenes with X. After Sora holds a conversation with him, Togyu impales himself, and ends up unconscious.
At that moment, Hiyo attempts to maim her former master, but is stopped by Sora.
- (to Shishidou Hiyo) "Enough already, you stupid brat! What do you mean, it's for your your sister?! You're just taking it out on them!! You are just taking out the frustration of you not being able to defeat the guy in front of you, on those who are weaker than you!"
- (to Himoto Sora) Bu-By "assault", you meant this!?
Reiko's weapon is a flail, and possesses a star, making it Sora's third star.
|p · e · t||Shitsurakuen Characters|
|Protagonists:||Aoi Tsuki · Himoto Sora · Izaki Koharu · Yagizawa Yuki · Oashi Tomoko · Date Reiko · Shishidou Hiyo|
|Himoto Sora's Allies||X · Asagiya Karin · Akane|
|Student Council:||Kajiwara Shinji · L · Houjou · Mitarai · Sumita · Togyu Shirou· Kuchinawa Haruka · Kawazu Tamao|