Secret Days (シークレットDays♡ Shīkuretto Days) is an otome game distributed as prizes in a competition hosted by Monthly Girls' Romance.
- A PV of the game was released by Square Enix on April Fools' Day in 2014.
- The character 'Umeno Sakitarou' is a self-insert of Nozaki.
- The character 'Kotomi Mikoshiba' is a self-insert of Mikoshiba.
- The protagonist, Umeko, is a self-insert of Nozaki's alter ego. She is meant to resemble Mamiko.
- The game's mascot is a 3D-model of a tanuki.