Undead Pappy

The vampire population once flourished the country, but they ended up in persecution due to the human uprising. Mikhail is the last surviving vampire, who is eccentric and loves humans. He had been living an eternity in solitude, until he came across a dying child soldier, Johann, and decided to raise him as his own son. For 16 years, Mikhail and Johann traveled the world together and now Johann is all grown up! Mikhail wants to marry him off, but Johann has a mind of his own...

(Source: BL Tsundoku Scans, edited)