Panel 1: Monster movies: Rodan, Mothra, and what might be Gameru in the far background.
Panel 2: Super Sentai/Power Rangers, the "Z!" might be a Jhonen Vasquez reference.
Panel 3: A monk type guy using an o-fuda, a catgirl, and possibly some samurai on the rooftops.
Junko is engaged in enjo kosai.
-chan = suffix used for children, people younger than you, or close friends.
Judging by the katakana on those banner/signs, they just left a ramen restaurant.
sensei = teacher