24Hours★Innocent Girl ~ A Slightly Dangerous Summer Vacation ~

The woman you saved during a walk was a mermaid.
Days with innocent Yulia, who knows little about human society.
What kind of future awaits us…?

On a summer day after being dumped by Akiho—rumored to be the biggest slut in your club—you meet a girl at an amusement park pool.
The girl introduces herself as Mayuka and makes an offer for compensated dating. Bewildered by the proposition from such an innocent-looking girl, you still carry the lingering expectation of getting to sleep with Akiho, and end up making a mistake…
A strictly business, money-driven relationship with schoolgirl Mayuka!

In a quiet, somewhat remote town, Hannah lives with her father and younger brother. Eventually the summer break comes, and with it the question: "How to spend the last summer before her senior year in high school?" Explore Hannah's town and its surroundings, and find out what opportunities may hide there.

Many women around the world have become infertile for some inexplicable reason. All hope for the continued survival of the human species has been lost... until now. During your summer vacation, you were forcibly taken to a hospital where it was explained to you that you have special semen that is the cure to the infertility issue. The salvation of many women depends on you. During your summer vacation, you are free to do whatever you like, such as getting a part-time job, falling in love and getting married, paying for girls with money, becoming addicted to gambling, and even committing crimes. Or, you can even save the world. This is your summer vacation after all, so spend it however you like! Explore various activities, including womanizing, sex services, gambling, tattoos, crimes, and interior decorating. Most women have certain conditions to meet, such as having the right techniques, a certain amount of money, or a particular weakness, in order for you to persuade them to have sex with you. Spy on, blackmail, or prank others. Commit crimes like stealing desserts or abusing authority, but beware of jail time. If the fear of a criminal record won’t hold you back- do as you please!

It's a day in summer holiday.
You recently started living alone in the city, and are beginning to get worn out by the busy days.
Noises of the town, complicated relationship with others... Momentarily, your heart yearned for a moment of peaceful rest in a quiet place
 
It made you recall your time back when you live on a small island.
Surrounded by nature, living a free life, the time of serenity...
 
Led by the nostalgia, you made a phone call to an old lady running a guesthouse at the island.
What came back was a cheerful welcome along with an unexpected favor.
「Our daughters will be on their own for a while, can you look after them?」
 
This marks the start of the 14 days of your summer break.
The beginning of special days with two girls in a nostalgic island.