Some of the side characters like Shikimori's friends might also gain popularity in the fanfiction. If the fanfiction gives them more depth and interesting storylines, readers could really get attached to them. For example, a friend who has a hidden talent or a mysterious past.
Another plot could be a time - travel scenario where Shikimori goes back in time and has to deal with her past self and the challenges that come with it. This could add a whole new layer of complexity to her character.
The unique characters make it popular. Shikimori herself is a very interesting character with her cool and cute sides. Her relationship with her boyfriend is also quite charming, full of sweet and funny moments.
The story is about a relationship. Shikimori's boyfriend often gets into some small troubles, and Shikimori is there to save the day with her unexpected coolness. It also shows their daily life at school and with friends, filled with warm and humorous moments.
The ending of the Shikimori manga is quite satisfying. The main characters reach a conclusion that feels right for their journey, and loose ends are neatly tied up.
The answer is: "OST song" refers to the song in the OST. OST referred to the original music in movies, TV series, and other film and television works, and the song part was the OST song. According to the search results, some OSTs of movies and television works included some songs, such as the theme song of the TV series OST of " A Thought of Passing Mountains," many of Zhou Shen's OST songs, and Yu Kewei's Top Ten Classic OSTs. Therefore, an OST song referred to the song part of the original music in a film or television work.