TV-Series
Description
Kashiwagi Rein, alias Rain, serves as a core member of the Sunset Ravens. She possesses medium-length black hair in a bob cut and purple eyes (depicted as blue in the anime). Her typical attire is a light-colored shirt layered over a black one-piece outfit with a skirt and dark stockings. Casual wear consists of a shirt and short shorts, while combat sees her in a large light-colored coat. After a significant timeskip, her look incorporates a hooded jacket similar to her coat, black tights, and shoes.

Despite being a first-year middle school student, Rein displays high maturity, acting as a voice of reason and showcasing strong analytical skills. She remains calm under pressure, even delivering insults while held captive. Preferring indoor activities, she dislikes losing internet access. She resents being called a child, later modifying this stance to assert her adulthood post-timeskip. Her survival strategy in Darwin's Game favors evasion, though she commits to fighting to protect her home and clan. She occasionally worries her jokes are hard to understand. Internally, she describes feeling divided between an emotional self and a detached observer, likening it to depersonalization. This duality enables composure in emotionally charged situations, like her parents' divorce, though she acknowledges envy toward those who express emotions more freely.

Two years before the main events, Rein dreamed of sinking in an ocean after learning of her parents' divorce and her father's overseas job relocation; she remained in Japan with her mother. She entered Darwin's Game via an invitation from classmate Tachikawa Mio, activating her sigil "Laplace" during an incident where she used it to save a friend from lethal glass shards. She later becomes the Guardian of the World Branch for World Line N following Shidou Izaya's death.

Rein's primary sigil, "Laplace," calculates physical vectors and probabilities to visualize near-future outcomes, countered by unpredictable actions exceeding conventional physics. She supplements this with sniper rifles, achieving documented success against targets over 2000 meters away. Post-timeskip, she gains "Gae Assail," a spear that nullifies other sigils on contact. As Guardian, she acquires abilities to teleport individuals and grant sigils, though teleportation initially fatigues her. Her athleticism improves significantly, demonstrated by maneuvers like flipping onto a bus roof and jumping off Greed creatures. Non-combat skills include advanced computer proficiency, having programmed from a young age and developing software to sync Darwin's Game data to her workstation. Her equipment features multiple sniper rifles in a carry case and a Skorpion vz. 61 submachine gun.

Post-timeskip character development shows Rein becoming more physically capable and taking on greater responsibilities as Guardian, directly engaging in combat to defend civilians during crises like the Greed invasion. Her motto shifts from strict conflict avoidance to proactive community protection. She forms a close friendship with Suzune Hiiragi, whom she shields from knowledge of Darwin's Game's dangers.

Trivia notes list her birthday as May 1, blood type A, and a preference for nattō-flavored Umaibō, which she stockpiles as an energy source.