Yume Nisshi revolves around Usotsuki (Lit. Liar). Much like other fangame characters, Usotsuki is unable/unwilling to leave her room.
Unlike the other fangames, however, you can bring the save item along with you while you're dreaming.
In this game, there are 16 effects to collect and no endings. As you explore Usotsuki's dreams, more doors appear in the nexus. The latest version of the game is version 0.02.