Not entirely sure how to translate the commentary - could either be "love you" (koishicha) or a misspelling of "Koishi-chan".
It's not super common, but I do come across some commentaries that just decide to omit the ん from ちゃん. I'm not sure if it's some trend or slang, but I've been seeing it for a while. These two examples are both from the same artist, but see post #6982095 and post #6982099. In a similar vein, I sometimes see "sensei" abbreviated to "sen."
