Following Dog Days, Bun seeks refuge at Akio's house after yet another fight with Daisuke. But when Daisuke calls, it's Akio who answers -- and has some choice words for him.

Miyamoto Kano's "Walker" universe timeline:

1. Are You Enemy?
2. Not/Love
   -- Not/Love dj - The Reason Why We Live Together
   -- Not/Love dj - Dog Days
   -- Not/Love dj - Demonic Conversations
   -- Not/Love dj - Brand New Lover
3. Heat (MIYAMOTO Kano)
   -- Under the Skin
   -- Lizards, Angels, and Daemons

The ones on ( -- ) are doujinshis. They give background or "add into" to some key points in the main story line. So you're not really missing anything even if you don't read it.