ishiki shizuku

Kasumi's twin sister, who looked identical to her except for their hairstyles, the absence of glasses, and her own upbeat and cheerful personality. Despite being infected with Medusa and left out of those chosen for a cure, including her sister, she remained supportive and encouraged Kasumi to take the opportunity to be saved. Their relationship became increasingly strained after Shizuku witnessed Kasumi attempting suicide, and again when Kasumi wished they could die together before parting ways, unable to accept a world without her twin. During this confrontation, Shizuku accidentally pushed Kasumi off a cliff, leading to her sister's death. This traumatic event caused Shizuku to awaken her Medusa powers. Transported to Level 4, still reeling from her sister's death, Shizuku created numerous abominations—initially blobs of quivering flesh with maws and claws that devastated the labs and massacred the staff. Through Zeus' mind-controlling program, these creatures evolved into the dinosaurs encountered by the protagonists at the beginning of the story. It was revealed that the monstrous behemoth seen at the start of the manga, later referred to as the "mother" of the creatures, was actually Shizuku herself, using the beast as an unconscious armor to isolate herself from the world. Throughout the story, Shizuku was often mentioned by Kasumi and appeared frequently, either in her monstrous form or through ominous apparitions, which were often Kasumi's delusions or unconscious mental links between the sisters. In the end, she appeared at the core of her mutated form, pleading with Kasumi not to uncover that she was merely a creation of Medusa and that her true self had died. With the death of Zeus, she too ceased to exist, her monstrous body crumbling to pieces and her essence fading away peacefully. (Source: Wikipedia)