Episode 4 titled "Kuku" maintains this balance and delivers a gripping experience as the plotlines and character dynamics continue to evolve. The episode skillfully intertwines two main story arcs: Harukiriko and Maru must confront a dangerous threat, while the children in "Paradise" face their own challenges. The character Kuku, one of the children, takes center stage as she eagerly tries to show Tokio real babies, unlike the ones they’ve seen in their sheltered world. Her journey to uncover the truth about these infants leads to some bizarre and revealing discoveries.

These babies are indeed strange, with faceless features and peculiar lower halves that lend the story an unsettling tone. The surveillance cameras’ inability to detect Tokio’s presence, along with a baby crying out his name, adds to the mystery of the unfolding events.

Meanwhile, the story explores the complexity of the relationships between the children. Shiro grapples with his feelings for Mimihime, Tarao struggles with an illness, and Tokio tries to make sense of the disturbing discoveries he’s made during the episode.

At the same time, Harukiriko and Maru face a terrifying creature that tests their skills and ingenuity. Kiruko’s quick thinking and Maru’s clever plan showcase their resilience and adaptability in dire situations. Their ongoing search for the bird logo leads to a humorous misunderstanding, highlighting their endearing partnership.