So there's a customer service desk at the back of the arcade, and he happens to walk past it. The painting is hanging behind the desk, above it. It's fairly noticeable. Also it's a certain someone so likeeeeeeee-
"Old hag...? Didn't anyone teach you to respect your elders-ah well...that's Yamato-he used to be the god of love...there's very few who still worship him now."
