This is pretty interesting - and funny! - just from the first chapter, and I'm into it. There's a lot to unpack here:
Pages 4 and 5 indicate that Ichika already knows she's gay, or at least that she's not into men. Her love at first sight with Aria a few pages later makes me think it's the former.
Also on page 5, her grandma's words of "If someone captures your heart, don't let them get away" seems to say that she had a relationship with Aria - or at least an unrequited love for her - separated for some reason.
During their first meeting, Ichika's too gay for Aria to be properly suspicious of her, to the point where even Aria notices (and is flustered by her).
Aria has no shame, and Ichika's a pretty good shot with that washbin.
Aria recognizes Ichika's teddy bear that her grandma gave her. Considering how Aria calls it "Beartrice", she was probably the one who gave it to the grandma in the first place.
Aria doesn't seem to surprised by that "burglar". Going by his dialogue, they definitely know each other - he's most likely a vampire too, which is probably why Aria's so ready to bash his head in. He wasn't expecting her to be so violent so quickly, though, which is weird when he opened up with "Back for more, I see". This burglar also appears to be Japanese, unlike Aria.
Also, I loved how Ichika's reaction changed from Aria just kicking the "burglar", to full on cracking his skull open. She was like "Violence is hot, but not that much violence!"
There's quite a few stuff left unanswered for the moment - What exactly was the relationship between Aria and Ichika's grandma Chiyo? What was in Chiyo's room that Aria (and the burglar?) were looking for? How did the burglar even get into Chiyo's room? I'm looking forward to where this goes.