Nasu - Blood Sealed, #1

Go to work. Come home. Repeat. Phil's life is boring and he loves every second of it. No excitement, no boyfriends breaking up with him over cereal in his underwear. When everything's predictable, nothing bad happens. But nothing good does, either. One night, when his best friend forces him to step outside of his comfort zone, he meets Shige who's too enigmatic to really be interested in him. He's trouble, but Phil can't help ignoring his own advice. Decades have gone by while Shige's kept himself locked away.
He's tired of the world, of humans and vampires. He was happy collecting dust until one day he wasn't. On a whim, he ventures out and meets Phil, setting them on a path that'll change them both. Whatever this is between them, it won't come easy. Plagued by distrust and danger from within and without, but if they survive, it just might be worth it.