Onigokko!

Maybe I was destined to become a permanent employee of the King of Hell in this life, and then spend the rest of my life happily with beautiful women. However, I was transported to another world because I mistakenly touched a button.
When I arrived in this world, in front of my eyes were two women who were changing their clothes and stroking each other's bodies. Because of my arrival, their movements suddenly stopped ......
"Peeping Tom!" What kind of anticlimactic opening is this?
Future technology? Time travelers? The Mobile Unit? An amusement park on the verge of bankruptcy? What kind of nonsense is this?
Let's rebuild the amusement park with Keon, a genius girl, and Dee, a secretarial girls in professional attire!! Find a way to get back.
Wait a minute. Why am I working at an amusement park when I'm in another world?

After being falsely accused and ordered to drop out of school, you are forced to hide in a dark room and live your life. You thought your life could not get any worse, but you fell into a scam of online nude chatting and got caught in the middle of a fight between the gangs and the WSA.
You are not only arrested and imprisoned by the WSA, you are even sentenced to death. You have to either be the dog of a young lady or the hostage of a ruthless killer to have a chance of survival.
You will make your own choice between the daughter of the head of the WSA and the daughter of a gangster.
Modern technology versus the slums, the WSA versus the gangs, third-party mysterious forces, and strange alien creatures - all of these conflicts are shrouded in an impenetrable fog that will shatter your past life. Start over, solve all the mysteries, and become the hero of the city.

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!

Toono Yuu, a Kazami Academy sophomore, eschews typical teen life for work――

"Youth? No time. I've got jobs."

Yuu's all about practicality, choosing part-time jobs over typical teenage fun. He manages his studies well and spends most of his time working for money. His childhood friend Hibiki and classmate Riri, who looks up to Yu, think he needs a change. They each try to get him to join a club.

Hibiki champions the "Action Club," nicknamed "Acti-Club"―― lively girls promoting "more youthful fun at school!"
Riri advocates the "Volunteer Club," nicknamed "Negati-Club"―― serious girls dedicated to "using youth to better the world."

Both relentlessly recruit Yuu――

"Not interested. Don't need youth."

Yet Yuu finds himself drawn into their world, despite his protests――
His predictable routine gives way to unexpected experiences.
How did this happen?

"Isn't it obvious?" his peers suggest.
"Brace yourself, senpai. Time to embrace your youth!"

What adventures await this reluctant teen!?