I'm not entirely sure as I haven't read it specifically. But generally, an 'isekai novel' often involves a character being transported to another world. Maybe 'jk haru' is the main character in this story who experiences adventures in a different realm.
Sadly, I don't have information regarding the author of this 'jk haru wa isekai novel'. It could be a relatively unknown work or from an indie author. You might want to search for it on specialized Japanese literature websites or forums where fans of isekai novels might be able to help you out.
It could be that the manga shows how the pesticide worker adapts to the strange new world, makes friends, and overcomes obstacles with his unique skills and knowledge from his past life.
I'm not entirely sure as I haven't read it specifically. But generally, an isekai light novel often involves a character being transported to another world. 'jk haru' might be the name of the main character. So it could be about Haru's adventures in a different world.
As the title implies, Haru is probably a central figure. There might also be other characters in the new world that Haru meets. For example, there could be a wizard or a knight who helps or hinders Haru's journey. However, without reading the novel, it's difficult to say for certain who all the main characters are.
Haru does love Legosi in the manga. It's evident in the way she cares for him, shows concern, and their shared experiences strengthen their bond, making it clear that her emotions towards him are those of love.