Me too!!! I am so damn curious
Theres actually a continuation of this manga with Kanchan's story, which explains more 8)
http://www.mangago.zone/read-manga/renai_rubi_no_tadashii_furikata/bt/ebd618fe1b9ef76dd5ee458671769b51_chapter-4/pg-1/
Ohhhh omg I read both of the mangas, this one first a long time ago and the renai rubi no tadashii one just a few weeks ago but I couldn't understand why the dude in the renai one kept talking about "what KIND of a person he USED to be." I finally understand now lol it connects. Was also wondering why he was staring at the photo. The photo was the same one in this manga with Yumi. Glad I came and reread this manga, otherwise I would never have known.
read how he got to that point here http://www.mangago.zone/read-manga/azami/
I want to know the reason why Kan chan was like that ;u;