I'm not sure what I feel about this, but I think when his mother said she hated him and asked him to leave the town, it's like releasing the spell she casted on him, Reiji was smiling after that.
tbh, I'd mad if this ended up being happy ending, heck I'd even be mad if they continued their lives, because it doesn't make sense, the characters are rotten to the core, they can't be saved.
Well, there is a cliche in manga, if a character stayed too long in an onsen, they will passed out. He said he was about to get out in page 13, so he's been there for a quiet some time...