That playful punch on pg. 7 was adorable. Marin has truly, hopelessly fallen in love with Wakana and I won't have it any other way. Go get him, girl!
Wakana has male friends now, that's progression too, for his own character. They were Marin's friends first, but I guess with this he's become part of the group too.
I don't remember if the black haired dude is named Kensei or Takeru, but he seems to be acquainted with Akira. You don't greet someone you meet for the first time with "you reek of tobacco" (especially not in Japan where politeness is paramount), maybe she's a cousin or a childhood friend.