After the first chapter with Hiroya's narrative as the story begins with a dream he had. Than it shows him working inside an office that he runs with two other men. He starts to think about his beginnings and he tells about his story on how he lived on an island at first and fell for a guy there. It also shows his horrible father. Something where you find out later that the dream is truly like a flashback.
I will say I'll stick with this story for many reasons and one of is that it truly sucks being allergic to the sun. I should know since I am allergic to it myself.
Hi no Ataranai Basho