ITS THE SONG AT THE LAST PANEL THERE WERE MUSIC NOTES WERE GETTING THE SONGGGG OMG OMG

accidentally disliked!! sorry

I'm pretty sure that's just the doorbell. The katakana says "pin pon" which is a pretty typical doorbell onomotopoeia. I imagine after dropping her off Koga went back home to get the album and has now returned.

if it is then thats good she came back but im rlyyyy hoping for their songggg alrdy