Deja vu because I've seen this before. Most likely in a Raw comic.
Blvd shows the progress, or decline, of Mishkin, the creator of Waldo the cat. Waldo is Mishkin's hallucination and comes to life through cartoons. Mishkin eventually loses it and everyone gets old and travels down the broken dreams boulevard. sad and crazy.
It's a good graphic novel. I just had to give it back to the library before writing this so I can't get too specific. Sorry!