I'm not sure specifically as I haven't read this light novel. But generally, 'koi' means love in Japanese. It might be about a love story that has something to do with twins ('futago'), like perhaps a love triangle involving twins that can't be separated ('warikirenai').
Sharing such stories is inappropriate as it involves adult and private content. Let's focus on positive and family - friendly beach experiences like building sandcastles or having a beach picnic.
The 'yuuki yuuna wa yuusha de aru visual novel' mainly focuses on the story of some brave girls. These girls are ordinary at first but are gradually drawn into a heroic journey. They experience a lot, like fighting against mysterious enemies, and at the same time, their friendship is deepened during these processes.
One characteristic is the isekai setting. The protagonist is transported from their normal world to a different, often magical world. Another is the use of magic. The characters usually have to learn to control and use magic in various ways to progress in the story.
The 'yuuki yuuna wa yuusha de aru light novel' could be centered around Yuuki Yuuna's journey as a hero. It may include her initial discovery of her heroic abilities. Maybe she starts off as an ordinary girl and then something extraordinary happens that thrusts her into the role of a hero. The story could also involve her moral dilemmas as she makes decisions in the face of danger. There might be a cast of supporting characters that either help or hinder her along the way, and the plot might unfold through different arcs that show her development both as a person and as a hero.
The 'shoujo shuumatsu ryokou light novel' might revolve around a girl's exploration in a world at its end. It could involve her encounters with different characters, each with their own stories and motives. There could be themes of hope, despair, and the search for meaning in a world that has seemingly lost everything. The light novel format would allow for detailed descriptions of the settings, which could range from ruined cities to desolate landscapes, and the girl's emotional journey as she traverses this post - apocalyptic realm.
There are many wonderful beach stories that are family - friendly. For example, a story about a family building a huge sandcastle together. They spent the whole day collecting shells to decorate it and had a great time competing with other families on the beach to see who could build the most creative one.
I'm not entirely sure which specific 'Sex on the Beach Story' you're referring to. It could potentially be a story related to the famous cocktail named 'Sex on the Beach'. Maybe it's about the origin of the cocktail, how it was created, and the different ingredients that go into it. Or it could be a fictional story set on a beach that has some sort of romantic or adventurous theme related to the name in a more symbolic way.
Well, it's hard to say for sure if it's popular. There are so many stories out there. If it has been picked up by social media or has some sort of viral element to it, it could gain popularity quickly. But without more information about what exactly this story is, it's difficult to gauge its popularity accurately. It could be that it's only popular within a small community of beach - lovers or cocktail aficionados who have passed it on through word - of - mouth.
Another possibility is that it could be a personal anecdote someone has named 'Sex on the Beach Story'. It could be about a memorable time at the beach, perhaps a romantic encounter or a wild adventure that happened on the beach and the person decided to give it this catchy name for their own reasons.