I'm not entirely sure as the title is rather specific and not a widely known mainstream visual novel. It could potentially be about a character who keeps repeating something and is unable to do something. Maybe it's a story of self - discovery and struggle within the context of a visual novel world.
There's no way to accurately determine the main characters just from this title. However, if we assume based on the title, it might be a first - person narrator, perhaps a young person, given the use of 'watashi' which means 'I' in Japanese. This character could be in a world filled with other supporting characters who either contribute to their inability to do something or are witnesses to their repetitive cycle.
This visual novel could potentially be centered around a female character who is the focus of the love interests in the story. The 'koi shinasai' part implies that there is an element of urging someone to fall in love. It may have various story arcs, like how the characters meet, the obstacles they face in their relationships, and how they develop feelings for each other. It could also have different endings depending on the choices made during the gameplay.
Since I haven't played it, I can't name the exact main characters. However, usually in a visual novel about love, there is likely a female lead who is the object of affection. There may also be male characters who are vying for her love or a male lead who is being urged to fall in love with the female character.
I'm not very familiar with this light novel specifically. But generally, a light novel often features unique characters and a fictional story world. It might be about some kind of adventure or relationship in a setting where there's a'maou' (demon king) involved. Maybe it's about the interactions that take place on a certain 'floor' within this fictional universe.
I'm not entirely sure as I haven't read this specific light novel. But generally, a light novel often involves unique characters, a fictional world, and a story with various themes such as adventure, friendship or self - discovery. Maybe it's about the journey of Aoi Hikaru on Earth.
Well, from the title 'kono naka ni hitori imouto ga iru light novel', it could potentially be a story centered around a male protagonist who has a sister. Maybe it's about their daily lives together, the challenges they face, or some kind of mystery or adventure that they get involved in because of their relationship. Light novels usually have elements of slice - of - life, fantasy, or drama, so this one could be a mix of those.
You can try checking major online book retailers like Amazon. They usually have a wide range of light novels available, including some relatively niche ones.
I'm not entirely sure as I haven't played this visual novel specifically. But generally, a visual novel with a title like this might be about a story where there is a sister figure in a particular situation within the narrative world of the game.
You might try looking for it in local bookstores that carry a selection of light novels. Some large chain bookstores often have a section dedicated to Japanese - style light novels.