Wakatsuki Kagami

I'll hit you if you say anything bad about Tsukasa,"

Wakatsuki Kagami, Down the Rabbit Hole I

Wakatsuki Kagami (若槻 鏡) is a childhood friend of Minakami Yuki, and a tsundere towards her. She's the older twin sister of Tsukasa, and is very protective of her, like they're two halves of one whole. Part of an existence that has been torn in half, she represents a happier time.

Appearance
Kagami has long purple hair she ties into twin tails with two ribbons, and purple eyes. She is always seen wearing the Kita High uniform with thigh-high socks except for a few instances in Down the Rabbit Hole I, when she's seen wearing a white and red Chinese-dress style top, and black shorts.

In her doll form, she's a huge stuffed rabbit doll that Hasaki often dresses up in school uniforms and pajamas.

Personality
Kagami has a very typical tsundere personality. She's hot-headed, uptight, brash, serious and gets flustered very easily when it comes to her childhood friend Yuki. She can get quite competitive when it comes to fighting for Yuki's affections as evidenced throughout Down the Rabbit Hole I where Takashima Zakuro becomes her love rival. She's incredibly protective of her younger sister Tsukasa

Kagami is a representation of a happier time for Mamiya Hasaki, the time when her brother gave her the rabbit doll he sewed by hand that would later be seen as Kagami. Kagami is a symbol of Hasaki's younger, happier self.

Plot
Kagami was originally a gift to Hasaki from her older brother Tomosane. After the tragic incident that ruined the lives of everyone involved, Hasaki clung on to Kagami and turned her into a symbol of her younger, happier self.

Kagami gained her identity as Wakatsuki Kagami from the delusions of Minakami Yuki and Mamiya Takuji, both of whom had erased Hasaki's existence from their memory at one point and saw her rabbit doll as a person - Kagami. Kagami got her human form from Takuji, who being an anime otaku, modelled her personality, appearance and name after an anime character. Yuki would often have her memories rewritten by Takuji which made her see Hasaki's doll as her childhood friend.

When Hasaki confronts Takuji after Tomosane's "death", Takuji orders his followers to gang rape and crucify Kagami in front of Hasaki, violating her precious memories. This marked the death of Wakatsuki Kagami.

Minakami Yuki
Minakami Yuki is a childhood friend of Kagami. Kagami is in love with Yuki and gets very flustered at Yuki's constant teasing. While Yuki makes fun of Kagami, she cares about her deeply.

Wakatsuki Tsukasa
Wakatsuki Tsukasa is Kagami's twin sister. Kagami is very protective of Tsukasa and never lets anyone get away with insulting her or making fun of her, even Yuki. Though Kagami is the older twin, Tsukasa's maturity makes her seem like the older one instead.

Mamiya Hasaki
Kagami is Hasaki's rabbit doll, gifted to her by Tomosane. Hasaki takes the doll everywhere with her and is deeply attached to it, projecting her feelings and memories onto it. Hasaki loses the doll when Kagami "dies" after being raped and crucified by Mamiya Takuji and his cult.

Mamiya Takuji
The creator of the human form of Kagami. Despite being her creator, he hates Kagami and Tsukasa, likely because they are a symbol of his younger twin sister Hasaki, who he despises. He eventually loses his cool and ruins Kagami by having his followers rape and crucify her, but he can never truly break her.

Takashima Zakuro
Only having met in the dreamscape of Down the Rabbit Hole I, Zakuro, Kagami and Tsukasa all start living in Yuki's house to compete for her affection. Zakuro and Kagami in particular being especially competitive towards each other.

Trivia

 * Kagami is based on the Lucky Star character, Hiiragi Kagami.
 * Despite being a representation of Hasaki's younger self, she is nothing like Hasaki in terms of personality or role. She's more like Tomosane than anyone else.