first, it's pretty obvious that Haruno is proto-Renako. not only they are both at the center of triangle love (Renako having love triangle after vol 4), but also they both having struggle to identify their own feeling toward person around them. during the story they learn and realized that they love those dear person(s). although Renako decide to accept love from both Mai and Ajisai while Haruno only accept Sayo's while seeing Rinna as a friend.
I love this story so much, it's feels so sweet and beautiful. the whole "seeing love arrow" seems like a gimmick, but it also help Haruno to realized on how and when she start develop her love toward Sayo. tbh, I assume in the end, Haruno decide to accept both Sayo and Rinna's love. I think that's the most ideal one. there is also a case where three girls going out with each other, so I assume that would be the foreshadowing to the outcome of this triangle love story. but nope. this is another case of "osananajimi wins" again I guess. nevertheless, I still enjoy the story so whether Haruno decide to going out with which one isn't really upset me.