Succubus Research Diary

The daring explorer Serena and the kindhearted succubus Nerisha meet by chance in the depths of the Underground. Succubus Research Diary is an adult visual novel about the unusual and very intimate relationship between the two women.
The Main Story
Nerisha
is a young adult succubus who has never had sex. This is something of a problem to her because succubi can't fully develop their magical powers unless they have some sweaty fun with humans or other humanoids. However, having high ideals of equality, Nerisha is unwilling to get herself a sex slave as most other succubi do.
Serena
is a human explorer who got separated from her expedition after something unfortunate happened. She's a mature woman with plenty of sex appeal that she doesn't hesitate to put to good use.
The two women
meet as Serena accidentally stumbles upon Nerisha's doorstep. After learning of each other's circumstances, they strike an unusual deal. A deal that involves the two of them having lots of sex...
The Afterstory: Serena's Services
Serena's Services is an additional story arc added in post-launch content updates. It is approximately 2 hours long and introduces three new characters to the story!
The final part of Serena's Services was added in the patch 1.5.0.
Features:
97 000 words (6-8 hours)
34 unique event CGs and a total of 307 variants
Rich background story about the problematic relationship of succubi and humans
The main story sex scenes have 5 stages with unique conversations
Have sex and conduct research to unlock more sex scenes
All the typical visual novel features such as unlockable CG & event gallery
The story takes place in a female-only fantasy world and includes both female x female (~70%) and futanari x female (~30%) adult scenes. All futanari content is optional.