Hanarokushou ga Akeru Hi ni

The Obinata Fireworks Shop factory is getting prepared for an administrative action for confiscation tomorrow. It has been six years since Keitaro has been holed up in a closed-down factory creating fireworks by himself, chasing after an illusion of his father who vanished. It is a story about three young people who overcome the extreme weather conditions, disasters, and environmental problems imposed on them and establish their own identities.

Synopsis from Anime News Network