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?

Amawa Hibiki is a young man just out of college, with an education to be an athletics teacher. He's been having a hard time finding a job since he graduated, so all his money has gone towards living expenses. When his landlady demands his first payment to live in her living establishment upfront, he heads to the local middle school to get hired as a teacher. However, the principal refuses to hire him without hesitation. She will not hire men as teachers and makes it clear that she hates all men, saying they put no love into their passions and work. Amawa does not give up and with the help of his landlady, he crossdresses as a woman without a second thought, and gets hired, so he can earn money and also prove the principal wrong. Now, he has to keep his real gender a secret, and avoid strange situations, including the affections of his students (from both genders).

Yoroi Takeshi is a carefree and somewhat naïve youth, who works as an assistant to the bumbling detective wannabe Kuruma Jo (who frequently proclaims himself the heir apparent to the title of Greatest Detective “Sherlock Holmes”). From their rundown and shabby office, they run a humble if not failing private investigation service. The spunky and cute Nanba Teru (who’s father owns the building when Jo and Takeshi reside in) frequently interferes in their affairs by threatening eviction (Jo is continually months behind in back rent). Since they rarely get any clients, they must resort to eavesdropping and spying on the Secret International Police Department headquarters, located in the building across from theirs in order to get their assignments. Unbeknownst to Jo and Teru, Takeshi has a deep secret. Not only is Takeshi the son of the International Police Department Chief but in times of peril and danger, mild-mannered Takeshi uses his trusty Poly-Met (Polymer Helmet) to transform into the Superhero “Hurricane” Polymer, a red suited masked man with incredible fighting abilities and superhuman strength. The only one who knows Takeshi’s secret is his lazy Saint Bernard, Daisaku, who always likes to provide cutting commentary to the audience (using his inner voice). Together Jo and Takeshi (as Polymer) confront and battle a myriad of evil organizations, criminal gangs, mutants and monsters as they fight crime in the future city of Washinkyo (Washington/Tokyo).