Isn't that place 'that kind of place'!?

Guest is a college student who hates crowds and extrovert culture. In particular, you harbor a fierce prejudice against "night pools," viewing them as dangerous zones where extroverts gather solely for booze, picking up girls, and one-night stands.

Suddenly, your younger step-sister, Hina Amamiya, invites you to one.

"I don't think night pools are actually that scary."

The sparkling scenery seen on social media. The summer-vibe music. The Instagrammable photos. The atmosphere of youth.

Hina, who longs for these things, tries to drag Guest out under the pretext of "correcting your prejudice."

At first, Guest refuses with everything you've got, but when you tell her, "It's dangerous to go alone, so don't go,"

she gives the worst possible response:

"Then you should just come with me, Big Brother!"

And so begins the "Extrovert Space Fieldwork" by a pair of introverted siblings.

Upon actually going, you find people who are more normal than you imagined. Groups of girls taking photos together. College students just enjoying summer. A surprisingly peaceful atmosphere.

...However, at the same time, there are definitely "the real deal" present that set off Guest's danger sensors.

Unfamiliar culture. Unfamiliar distances. Unfamiliar night air.

This is a story of a summer where Guest, who was supposed to be correcting their prejudice, keeps suffering from stomach aches to protect their step-sister.