Hikaru has always believed herself to be just a normal high school girl...well, as normal as a teenager with a genius mad scientist for a father. She spends her time with her best friend, day dreaming about the boy she loves and watching her favoite super hero show. One day, the past that she has knows nothing about comes back to haunt her. She is shocked to learn that she is the last surviving member of royal line from a far away planet. Even more, she finds out that she has been protecting the ultimate armour and that it can decide the fate of the entire galaxy.

The skilled craftsman Kuroda created artificial humans called Hybrid Child—creatures who are neither machines nor dolls, but rather a reflection of the love shown to them. While they can feel human emotions and have their own consciousness, they are not real humans and require love to grow. Kotarou Izumi is the young heir to the noble Izumi family, so it is frowned upon when he brings an abandoned Hybrid Child he found in the garbage into their household. His family even attempts to throw away Hazuki—Kotarou's name for the Hybrid Child—multiple times when he is not paying attention. But through overcoming these obstacles, their love and the bond connecting them grow stronger. However, ten years pass before a horrifying realization dawns on them: a Hybrid Child might not have an endless life span. Hybrid Child is a collection of three short love stories, depicting the relationship between the artificial humans and their owners.

Minato visits a recitation at an anime event with his friend. He is captivated by the voice actors' performances and decides to enroll in Suidoubashi Animation Academy. There, he meets Chikako, who used to live in the room he is moving into and who left a message in a USB drive. Minato, who aims to be a voice actor but is unable to put himself into the role, and Chikako, who lives with a past trauma, encourage one another and try to improve themselves. With the help of seniors such as Ryouta and Kei watching over them, they try to mature. As they stumble and worry, what lies ahead for them both?

On a cold planet of ice and snow, mysterious creatures suddenly have appeared from the dark underground and have begun to attack the inhabitants. Can humanity survive the terror lurking beyond the horizon?