Chibi Vampire, Vol. 6 by Yuna Kagesaki

Clueless Kenta is finally getting closer to figuring out that Karin has a secret crush on him. But everything explodes - literally! - when Kenta's grandmother hires a detective to track Kenta down and bring him back to their hometown. A case of mistaken identity turns tragic when Karin's family bans her from seeing the very person she can't live without! Will Karin finally be forced to confess her love?