Elena Aoki, Clair Aoki's older sister by two years, gained monstrous powers following contact with an extraterrestrial entity. She then killed their parents, viewing her corrupt politician father and mother—who engaged in an affair with a younger coworker—as hypocrites enforcing strict standards on their daughters. Elena staged their deaths as a poison gas accident, discrediting Clair's accusations. Despite this violence, she spared Clair, insisting the act was for her sister's benefit and gave her a wish-granting coin. Elena later allied with Naoto, leading a group to collect 100 such coins for a powerful wish resolving past conflicts. At Yamada Cram School, Elena formed close bonds with Shuichi Kagaya, Honoka, Kaito, Naoto, and Aiko, eventually developing a romantic relationship with Shuichi. She was notably kind to newcomers like transfer student Sayaka Koyanagi, helping them integrate. Aiko's suicide and Honoka's subsequent wish to assume Aiko's identity triggered tragedy. Misunderstanding, Kaito used his wish to create a monstrous entity killing anyone forgetting Honoka's name. To protect Shuichi, Elena used coins to transform them both into monsters and erased his memories of their relationship. Elena exhibits profound emotional instability, embodying a volatile yandere archetype with intense, possessive feelings for Shuichi. She shifts abruptly between shy, apologetic behavior and murderous rage, especially when others intrude on her connection to him. Hearing a female voice (Clair) within Shuichi's monstrous form, Elena decapitated him in jealous fury, immediately regretting it. She believed the interior of his form was exclusively for her. Despite her volatility, she displays genuine love for Clair, refusing to harm her and offering guidance. Elena commands fierce loyalty from allies like Subaru, who obeys despite disdain for authority; she occasionally shows concern for him. Her abilities, granted by the alien in exchange for coins, include transformation into a large, shadow-draped ghost-like monster with red eyes and a skeletal mouth. This form grants immense strength—effortlessly tearing off Shuichi's head—and allows disassembly into ash or shadow matter for swift teleportation during combat. She also manipulates memories, erasing herself from Shuichi's recollections. Her heightened presence induces overwhelming fear, noted in Shuichi's terror upon contact. Shuichi and Clair discerned through enhanced senses that Elena committed numerous murders beyond her parents'. This history paints her as a remorseless, lethal figure. While occasionally expressing regret, like apologizing to Shuichi, her instability and brutality remain defining. Her complex motivations intertwine warped protectiveness toward Clair, obsessive love for Shuichi, and ruthless pragmatism in pursuing goals through manipulation and force.