Can anyone tell me what Kimi to Boku is about?

आप know, आप could always look this stuff up on Wiki..

It's like a comedy, slice of life anime. I've heard it has romance in it too. But yeah it just follows five guys in their high school days.

Basically what RobinFan said

It doesn't really have a "story" but it does have a little bit of narrative such as character development, their backgrounds, relationships etc. Think of it as a male lucky तारा, स्टार but और serious (but still funny)