It's simply a series of loli erotica aimed at masochistic gentlemen (with occult themes).

(Source: Afterword from chapter 3)

Chapter 1
A loli succubus relentlessly milks her prey. There are worse ways to go.
The last is a sweet sweeeeet sweeeeeet happy ending.

Chapter 2
A cursed doll appears in the room in this tale of sweet reverse NTR and sacrificed life.

Chapter 3
Being sexually played as a toy of two girls who you meet in a hot spring resort.

Chapter 4
Three girls sexually bully an oniichan.

(Source: DLsite English)