Vampire Syndrome

A Seymour Original (シーモアオリジナル)
Shun meets his ideal boyfriend, Mitsuomi, on a dating app. It seems like smooth sailing after several dates, but he begins to feel as if Mitsuomi is keeping a secret from him. No sleepover dates, no invitations to his house, and he even makes fun of me, saying, "Do you think I'm a vampire?"! As Shun's anxiety grows he decides to take a gamble... A forbidden BL with a mysterious handsome man!

(originally from cmoa, translated and edited with DeepL translate)