Succubus Sessions: Mami Mamiya's Sweet Slice of Hell

In this game, you play as Fujita Hiroyuki, a high-school student who seems to have more interest in romance than in his studies. In his school there are several pretty girls, and his goal is to be nice to one of them, to make the right decisions when talking to her, and ultimately to win her heart.
 
Remake of the original PC version featuring a completely revised script, with some of the heroines having completely different stories as a result, full voice acting for all characters except the protagonist, new art, and mini-games.

Uchihama Academy has seen an increase in enrollment in recent years and as a result, a new school building will be constructed. The story takes place during the final school festival in the old school. All the club leaders decide to give it their all to make this the best school festival. Sou is a member of the notorious astronomy club, which basically solves the various issues in the student council's place.

On one day, he stays in the school late at evening because he got slightly injured by the judo club and is healing his wounds in the infirmary. Suddenly, the building shakes. Shocked, he runs up the stairs to where the shaking seems to have centered, and there he encounters a mysterious naked girl, who at first appears to know him. On the next day this girl, Yui, seeks out the astronomy club, expressing her desire to join.

Under the rule of two great kingdoms, the continent of Maygard once enjoyed a period of prosperity.

However, that prosperity became a thing of the past once the continent came under attack from the Demon King Hamehameha and her formidable magical power... Since then, humanity has gradually been losing ground to the Demon King's forces.

With the survival of humanity at stake, a Hero arises to defeat the Demon King. Heading on a journey together with new allies and two princesses with whom he overcame a sage's trials, the Hero seeks to obtain a sacred relic which is said to vanquish demons.

However, the Hero and his party meet an untimely demise when they encounter a surprise-attack by the Demon King. With humanity's last hope lost, it seemed like the world was all but in the hands of the Demon Lord...

In his fading state of consciousness, the Hero extends his arm towards his captured party members. In that moment, the Hero hears a voice pleading for help somewhere deep in the darkness.

"Someone please help me..."

Drawn to the voice, the Hero's spirit is summoned by Julietta, a princess from a faraway land being held prisoner in the Demon King's castle. The two quickly figure out that Julietta's desire to escape and the Hero's desire to rescue his party members are aligned with one another.

When Dr.Ben Johnson and his wife Dr.Claire heard about the mysterious Moonflower and its amazing healing properties, they wasted no time heading to an island in the middle of the Pacific to hunt for the fabled plant.

What they didn’t expect to find there was the Aimumu, an ancestral tribe who had been watching over the island for centuries and guarded the secrets of the Moonflower from the hands of outsiders. To complete his ambitious research and make a name for himself in the halls of science, Dr Ben will need to earn the tribe’s trust.

From outta nowhere, you've found your bachelor pad being the defacto hangout zone for a trio of gorgeous gyarus! If your brain wasn't so full of lewd fantasies, maybe you would have paid more attention to their conversations, talking about weird stuff like "power spots" or "magical energy."
...Well, whatever! The instant you get a moment of privacy, you can jack off while their sweet smell still lingers in your room!

As you are out running an errand for the gals while they crash at your place, demons appear, running rampant on the streets. Before too much chaos is caused, the Starlight Girls, the local troop of Magical Girls, in-case it wasn't obvious, arrive!

Instead of fleeing the scene, your prefrontal cortex is clouded by a thick fog of horny thoughts, as you're watching their boobs and butts jiggle around as they activate their magical abilities. Sometime between the battle starting and drool dripping from your mouth, the red-headed magical girl is sent hurtling to the ground in front of you! As you summon your courage, you run over to try and protect the fallen hero, when suddenly a blinding FLASH bursts forth from your house reinvigorating the magical girl you're holding in your arms, as she quickly rejoins the other two, and the trio waste no time hitting their fully charged EX finishing move, STARLIGHT FINISHER! Wiping out the demons and saving the day!

When you scramble home, Chika, Miyu, and Mei are nowhere to be found. You expected the three gyarus to be angry, having been kept waiting for you to return with their snacks and drinks. Maybe after your encounter with those demons, your karma helped you dodge the wrath of hangry gyarus for tonight...

The next day after recovering from your ordeal from the day before, armed with fresh new fap material, you're ready to get to work when, knock knock, Chika comes barging in, dropping work shattering lore in the form of a "tl;dr, me and the other two are the Starlight Girls and you might be the chosen one who can channel magical energies to boost our powers!"

Well that explains why they hang around you so much at least. Today she wants to find out how you managed to give her a mana overcharge yesterday during the fight with the demons. The revelation you two have is; the hornier you get, the more mana that gets produced! So, after a little groping, and a little twerking, a radiant aura flares up from your crotch, bursting through your pants.

Chika is left awestruck! Looks like she is going to enjoy the mana milking process maybe even more than you are! With the exposition out of the way and your objective clear, its time to conquer the bodies of the Starlight Girls with your cock, so they can spend their day fighting monsters and their nights using their bodies to milk you dry of every last drop of your special mana!