Chaoling You Shenme Guanxi

Lin Jia-Ling, who looks just 17, is actually in her thirties and has decided to go back to school to finally get her A-levels. In addition to her evening classes, she also works as a maid in a mysterious castle. The young master of the castle is always shouting that he wants to marry Jia-Ling. Unexpectedly, he is in fact the real master of the castle and, incidentally, a vampire over a thousand years old! (Source: Mangas.io, translated)