Is Kasen's speech bubble just gibberish? The random mix of Latin and Japanese characters makes me think so.
It's basically the Japanese equivalent of the Tumblr RANDOM LETTERS ALSDKFJH;OPMCUCOQSIJRUTUXPOZMXLEWODJFJTBSHMEK.JBNOF thing. It's done a very specific way -- by swiping your fingers across the top two rows of the keyboard (qawsedrftgyhujikolp;); I think one thing that made it popular was that it spells out "fujiko" completely at random in the middle.