Wait-wait-wait... Her OLDER sister in highschool yet she prostituting herself???

It's seriously a trope to have characters like this show up that just force themselves on the main characters and force dramatic development. The irony being, after all the "drama", will probably be friends or more involved in the story and not as an enemy, even though they are heavily introduced as one.

even the character not that likeable, at least give interesting development...

Oh ho, an actual interesting development and characterization too. Nice to see it wasn't gonna spin it's wheels for a while.

This match is going to be at a stalemate for a very long time.

I really wanted to see the kind of face she made when her sister threaten to kill Wataru.

Guess she's changing schools!

Little bit of an S and a bit of a siscon. Hmm, alright let's see what else she can do.

Boy am I so glad I stumbled upon this manga. Its really fun!

Is that Kim Jong Un at page 12? ?