Beautiful but so sad, one should definitely start with this one, I accidentally ended up reading the series backwards.
The order should be:
Azami (Prequel)
Sabita Yoru Demo Koi wa Sasayaku
Renai Rubi no Tadashii Furikata (Spin-off/Sequel)
Narrow - Place collection (Side story)
Hadakeru Kaibutsu (Sequel)
Azami