Silver Lining | BSD [shin soukoku]

Finding out that a lie has pervaded years of your life isn't exactly a great way to end a mission, especially when it results in complete ignorance about your own biology. At twenty years old, Akutagawa had thought he was done learning about himself, but that doesn't seem to be the case at all. As it turns out, he hardly knows a thing.

Alternatively, asexual "beta" Akutagawa finds out that he's actually an omega and has to figure out how to deal with his first ever heat (a series of unfortunate events that ends with Aku getting railed within an inch of his life).
(crossposted from ao3)