Kokone Takatsu is an android who appears as a major supporting character in Yokohama Kaidashi Kikou. She is a production model designated A7M3, which technically makes her a younger sibling model to the protagonist Alpha, who is an A7M2. She works as a courier for a company called Musashino Correspondence. The name Kokone was one she chose for herself when she first arrived at the training institute.

In terms of personality, Kokone is described as sweet, shy, and somewhat intellectual. Because her job as a courier brings her into regular contact with people, she has more experience interacting with humans than Alpha does, and she is sometimes able to pass for a human. Despite being a robot, she displays a gentle and reserved demeanor.

Her role in the story begins when she delivers a package containing a camera and a message from Alpha's owner, marking the first time Alpha meets another robot. The two quickly become close friends. Kokone's motivation evolves from her initial task-oriented courier duties into a deeper curiosity about the history and nature of androids after she meets Alpha. She becomes interested in the origins of the A7 series and her own identity.

Kokone's development over the course of the series involves a transition from a rigid, professional courier to a character who actively seeks self-discovery and emotional awakening. She grows more introspective about her place in the world and the legacy of the robots. Her key relationship is with Alpha, whom she views as an older sister figure, a mentor, and a confidante. She also has significant interactions with Maruko, another android living in the city, with whom she shares a complex and affectionate friendship.

Notable abilities include the fact that, unlike Alpha, Kokone can digest animal proteins, a trait that allows her to eat normal food. Her courier work gives her familiarity with traveling and navigating the world beyond Alpha's rural coastal area. She is often seen riding an electric scooter as part of her deliveries.