The target the brothers are ordered to watch. She was born on the same day that her sister Momoka died and believes that she is Momoka's reincarnation. The death of her sister caused her family to fall apart; her parents divorced and she lives with her busy mother. She possesses Momoka's diary, the entries of which she follows religiously for the purpose of "destiny". It is because of these entries that she stalks Keiju Tabuki, who was very close to Momoka. She believes that by replacing her sister, she will be able to bring her family back together. This includes fulfilling Momoka's wish to have children with her boyfriend.

The middle child of the Takakura siblings and the only biological child in the Takakura family. He is uneasy at thoughts of performing any morally ambiguous deeds. He is assigned to obtain Ringo's diary, believing that it is the Penguindrum, and hesitates after being told to obtain it by any means necessary. He accompanies Ringo as she follows their teacher, and the two become close.
In the novel adaptation, Shoma is the narrator.