Mamori Tokonome is a sixteen-year-old girl who serves as one of the main protagonists of Valkyrie Drive: Mermaid. She stands 140 cm tall, weighs 38 kg, and has dark pink hair worn in high braided pigtails, brownish hazel eyes, and a well-developed chest that belies her small stature. Her most notable physical trait is her short height, which often causes others to mistake her for a middle school student and gives her a complex about her appearance. She is classified as an Extar, a carrier of the Armed Virus who can transform into a weapon when sexually aroused by a compatible Liberator. Her weapon form is a sword, and she is partnered with the Liberator Mirei Shikishima. Unbeknownst to Mamori herself, her latent power is far greater than that of the other inhabitants of Mermaid Island, and her compatibility with Mirei allows them to unleash the Valkyrie Effect, the ultimate manifestation of the Armed Virus that can manipulate or even cancel its effects in other carriers. Mamori's personality is gentle, obedient, and polite. She is naturally naive, innocent, and avoids conflict whenever possible, preferring peace and harmony. Despite her desire to stay out of trouble, meeting Mirei draws her into a series of dangerous incidents on Mermaid Island. Her surname, Tokonome, is written with the same kanji as the word for virgin, a fact that makes her uncomfortable when people misread or tease her about it. She enjoys reading in her spare time. Her backstory reveals that she overheard her parents discussing an illness when she was young, but she did not fully understand its significance until she was abducted from her school gym class and taken to Mermaid Island. Over the course of the story, Mamori undergoes significant personal growth. Initially shy and hesitant, she gradually becomes more confident in her abilities and more willing to stand up for herself and her partner. She learns to trust her allies and confront her fears, driven by a strong desire to protect those she cares about, especially Mirei. Her relationship with Mirei is the emotional core of the narrative; the two develop a deep romantic and partnership bond that enables them to fight effectively together. Mamori also interacts with other characters such as Kasumi Shigure, Meifon Sakura, the biker duo Lady Lady, and the governor Akira Hiiragi, but her loyalty and focus remain on Mirei. Her primary motivation is to survive the island's battles and eventually find a way to return to normal life, while also safeguarding the people she comes to love. Her role in the story is that of a central Extar whose unique power is key to the island's conflicts and the resolution of the Armed Virus phenomenon.