Oukoku Douwa

An omnibus of 3 short visual novels. Linear paths, no branching options.

The Antisocial Prince and Thorn Princess
Originally released for April Fools Day, 2012.
A romance between a shut-in hikikomori (age 22) and the princess of the next kingdom (age 19).

Mermaid Crown
A short, specially created work for this omnibus.
The story of a stubborn princess betrothed to someone she's never even met.

The Glass Slipper
About the magical girl-in-training who cast a spell on Cinderella, and a prince.
Comedic and romantic skit-like story.

[from DLsite English]