Manga Club Advisor wants to support Saeki Sasara

At Higashikoi Academy, where the protagonist (you) attends, male students have been disappearing one by one.
Why are only the boys disappearing? Who is doing it, and why?
On the day of your date, you are attacked by female students calling themselves the “Seduction Club,” and you set out to uncover the truth behind the Seduction Club.
There, you must discover the school’s hidden “other side”.
 

Club activities.
Looking back, it's a moment of youth that passes in the blink of an eye, but group activities take up a large part of student life.
"Would you like to have tea?" This was the reverse pick-up I'd dreamed of! But it turned out to be an invitation to join the Tea Ceremony Club.
It was perfect for me, as I hadn't decided which club to join. The Tea Ceremony Club had cute seniors and a beautiful teacher! I thought this would be a fulfilling youth, but I was wrong.
Yes, this was the "Sadistic Club" in disguise as the "Tea Ceremony Club"!
A sexy-looking woman attacks me like a zombie, strips me naked, ties me up, and footjobs my dick in front of everyone in the club, making me ejaculate in an instant!
The sad sex of a virgin. "So this is a masochist..." I couldn't help but burst into tears at her arbitrary judgment of me as a masochist. The seniors were ecstatic... What? That look of accomplishment on their faces...
"S is service, masochist is hospitality" - what's that? Using masochist men as bait to attract loads of dominant women! What's that?
All of the seniors are very interested in S&M! The days of training to become the ideal masochist man begin now.

The organization where spiritual ability holders gather, “Underworld Entertainment Club”.
The protagonist is ordered to “investigate” a room that has become a den of lustful ghosts, overflowing with sexual desire.

The protagonist accidentally stumbled into a mysterious billiards club and encountered a variety of billiard angels inside.
Strive to defeat them with your billiard skills! Victory will earn you rewards from the billiard angels!
Can't wait any longer? Go challenge these billiard angels right now!

The first rule of Anal Club is that no one talks about Anal Club.
The second rule of Anal Club is that no one talks about Anal Club. We insist. Unless you're telling a girl who enjoys anal sex.
The third rule of Anal Club is that there must be no more than one guy in the room. The number of women doesn't matter.
The fourth rule of Anal Club is that sex ends when you've fucked a girl's ass and come inside it.
The fifth rule of Anal Club is that you can't leave if you've only fucked one ass that night.
The sixth rule of Anal Club is that erotic clothing is allowed in the rooms, but nothing that covers the parts we all want to see.
The seventh rule of Anal Club is that each sexual encounter ends when all participants want it to. Only then will the room's door open, and you can leave.
And the eighth and final rule of Anal Club is that if it's your first night at Anal Club, you have to fuck three asses.