Older gay seme x younger gay uke PART 1

Disclaimer: For uke's case, he is gay since his unrequited crush is a guy. For seme's case, he is a mythological creature which makes it hard to determine his sexuality. He can be queer, demisexual, gay, bi or straight. For my own assumption, I assume he is gay.

Prequel:
1. Ashita, Kare no Bed de
2. Nemurenai Koibito
3. Kusuriyubi ga Shitteru
4. Mou Kimi o Matanai

Spin-off of Chizuka-san Ni Tsutaete that sets four years after the event of latter's Chapter 3-4.

Disclaimer: It has a little bit of seke. But, in my case, I consider the vampire as the seme. For seme's case, he seems like a bisexual or gay maybe out of his way of seducing them as food. For the benefit of the doubt, I consider him gay. For uke's case, it is no doubt.