Koishite Kiss shite Kanjaitai is a mediocre yaoi, it brings nothing new, and its not original at all, but its actually quite good. Lets start with the good things. For starters, I absolutely love the fact that this manga is not toxic and it doesn't have questionable behaviours, considering the fact that most yaois are literally more toxic than the whole kissing booth trilogy together. Also the art is completely beautiful, it's quite simple but at the same time it feels really unique. Now, moving on with the "bad" things (and I put the word bad in quotes because I don't think they necessarily ruin the manga). The storyis pretty simple and generic, it's also really fast paced (REALLY FAST PACED) and 50% of the manga is literally s3x scenes and I mean, that's fine, I wouldn't care if those parts had to do with the story or if they helped the story move forward or give more complexity for the characters, but they're just there...
The characters are bad, the only thing they talk about is each other, they don't have a motivation, goals, hobbies, problems, absolutely nothing. The only reason they're likeable is because of their dinamic and because they're cute together as a couple.
In general I think this manga is good if you just want to enjoy a cute yet sexy yaoi, dont take it too seriously and just enjoy it