The plotline with the teacher made me thought this manga had some potential but... alas, it never grew out of its mediocre, disappointing & repetitive fetish shell. So don't expect this manga to be anything better than that. I get why KissxSis became so influential, but after having read every chapter, I cannot, in good faith, recommend anyone to do the same. Just drop it around chapter 90 something (or when you start to get bored/confused, 'cuz trust me the manga won't get any better). I'd hate this manga much, much less if it actually ended at that point
Don't get me wrong - the early chapters are amazing. The ecchi's out-of-this world, and the comedy lands almost everytime. I laughed my ass out when this manga - first released in 2005 mind you - said that expecting something ecchi to come out of Twister is "clichéd". Then it attempted to have a meaningful arc, which to be fair was fanstatic, but that's when everything went downhill. It's clear the author didn't actually want the series to be too serious, and to go back to its funny ecchi root. But the author couldn't just undo the plot, which is why they started to blue-ball the readers with developments, both romance and characters-wise, that never went anywhere. And trust me, this went on for WAY longer than it needed to be. Frankly, it's a total waste of your time. If you want to experience KissXSis, watch the OVA adaptation, it has the same disgusting (in a loving way) charm and comedy and actually ends before it gets too stale