Summary because translation takes time I don't have now: Miss tells Myon to wait under the Reimu statue and leaves. Myon waits day after day, barely managing to keep her badge. Eventually Miss returns with a gold badge Yuuka and is surprised to see Myon still waiting for her. That's when Myon realizes that Miss was never going to return for her. The exterminator saves her from death (anti-yukkuritis or whatever), and since he sympathizes with Myon (apparently he was abandoned too or something) he takes her as a pet.
Summary because translation takes time I don't have now: Miss tells Myon to wait under the Reimu statue and leaves. Myon waits day after day, barely managing to keep her badge. Eventually Miss returns with a gold badge Yuuka and is surprised to see Myon still waiting for her. That's when Myon realizes that Miss was never going to return for her. The exterminator saves her from death (anti-yukkuritis or whatever), and since he sympathizes with Myon (apparently he was abandoned too or something) he takes her as a pet.
So the owner threw away a pet for another pet. Just goes to show how there is no justice for people with the yukkuri universe.
Summary because translation takes time I don't have now: Miss tells Myon to wait under the Reimu statue and leaves. Myon waits day after day, barely managing to keep her badge. Eventually Miss returns with a gold badge Yuuka and is surprised to see Myon still waiting for her. That's when Myon realizes that Miss was never going to return for her. The exterminator saves her from death (anti-yukkuritis or whatever), and since he sympathizes with Myon (apparently he was abandoned too or something) he takes her as a pet.
Its a yukkuri version of the story of Hachiko (with a happy ending.) The statue and background when Myon is waiting for Miss is a reference to the real world Hachiko statue outside of a train station in Japan (its a popular gathering spot in anime/manga)
(And by happy ending, I mean actual happy ending. The real life version ends with the dog dying while waiting his master, who never showed up because he died while at work (summarized).)