Rena Ryugu, born Reina Ryugu in Hinamizawa, moved to Ibaraki as a child following her fashion-designer mother’s career. Her family fractured when her mother’s affair with a coworker triggered a bitter divorce, which Rena rejected alongside her mother’s subsequent pregnancy. This rejection spiraled into violent breakdowns, culminating in her attacking classmates with a baseball bat and shattering school windows. Hospitalized, she blamed hallucinations of Oyashiro-sama’s curse, believing returning to Hinamizawa would grant safety. She renamed herself “Rena” by omitting the “i” from “Reina”—symbolizing the excision of “icky” influences, though she later reconciled with positive “i” associations. Cheerful and nurturing yet prone to volatility, Rena fixates on collecting “kyute” (cute) objects, triggering frenetic “Cute Mode” or “Take Home Mode” episodes where she aggressively pursues coveted items or people. This contrasts her sharp deductive skills, enabling precise crime-scene reconstructions or detection of concealed social tensions. She harbors visceral hatred for lies, erupting into violent “Uso da!” outbursts when deceived. Physically, Rena sports asymmetrical orange hair, lavender-blue eyes, and a youthful demeanor. Her school uniform features a sailor collar with a yellow ribbon, while casual wear includes a white dress with purple accents, thigh-high socks, and brown boots. Post-1988 timelines depict her as an adult in a purple business suit. Her narrative shifts between heroism and antagonism: in *Tsumihoroboshi-hen*, she murders scam artists Rina and Teppei to shield her father, then takes classmates hostage under Hinamizawa Syndrome’s influence until Keiichi intervenes. *Minagoroshi-hen* reveals her strategic manipulation of village leaders to expose Satoko’s abuse, balancing aggression with emotional control. Relationships oscillate between playful rivalry and trust with Keiichi, tinged with romantic ambiguity, and protective “kidnappings” of younger club members like Rika and Satoko during “Take Home” episodes. Mental instability defines her core: delusional parasitosis convinces her maggots infest her blood, driving self-harm rituals to “purify” herself—symptoms later diagnosed as Hinamizawa Syndrome. Though stress reactivates these struggles, she cultivates resilience through self-awareness and friendships. Post-canon stories like *Rei* portray her adulthood, attending university and raising a son, Kihiro. Legacy elements include a bloodstained cap recurring across arcs and her signature weapon evolving from an axe to a nata. Cross-media appearances span collaborations in *SINoALICE* and *PUBG Mobile*, while *Kizuna* arcs connect her to murder probes involving childhood peers.