Definitely a different kind of dark than LiL. I would say Winds of The Destiny is probably as lighthearted as it gets with VNs created using Koikatsu. I could definitely suggest other lighthearted VNs, some that are more lighthearted than anything suggested, but none of them are Koikatsu based. Most are in one of Illusion's more photo realistic style games like Honey Select, Honey Select 2, or Sexy Beach Premium Resort.Just... like me and alex2011 Have said, despite JJRobbie's proclamation, Out of touch isn't lighthearted at all. Nor is it really anything like Lessons in Love. There's some not so great stuff that happens in it.
I can't help you with what you're looking for, maybe School of love: clubs? But there's really not too many "lighthearted" vns unfortunately.
JJRobbie if you're fine with that, I could suggest Glassix, which has more of a sandbox play style to it and is made using the third of those three photo realistic games I listed. There's also Harem Hotel, which has pretty good writing, is more of a VN like this, and is much more lighthearted, this one uses the original Honey Select.