Yume no Shiro is a one volume work by Masami Tsuda and consists of 3 short stories. Masami Tsuda is famous for Kareshi Kanojo no Jijou, or KareKano for short. These stories were drawn while KareKano was still running so the artwork is quite nice.

It's all about love couples. Also, there is a thread running through all three stories. That's a magician who helps the people. Who are the people he helps?

1) Inside the Forest

2) I'm a Mermaid

3) The Castle of Dreams

[Source: Baka-Updates Manga]