The secret that Narumi reveals to Kei is that they are not actually biological siblings. Narumi was adopted into the family after her own parents died and Kei's parents took her in. However, Kei had no knowledge of this and is shocked to hear the news.
As Narumi begins to exert control over Kei and Kana's relationship, tensions rise and the truth about Narumi's past actions begin to surface. It turns out that the stabbing for which Narumi went to prison was not completely unprovoked, and that she has a history of violent outbursts.
As Kei struggles to come to terms with the fact that Narumi is not his biological sister and the growing distance between him and Kana, Narumi becomes increasingly unstable and possessive. The situation ultimately spirals out of control, leading to a shocking and tragic conclusion.
Helpless and Reckless is a tense and emotionally charged drama that explores the fragility of family bonds and the consequences of unchecked violence and aggression.